It's heavily implied clothes don't change. Even the Heartbeast ability does not change clothes, Falke, the Bjornaer Prima has a magical ankle chain which has a spell in it just to transform her ankle chain when she transforms into a bird.
I've found that this contributes to the game nicely. Bjornaer magi, and skinchangers have completely different attitude to nudity, and it's weirding the other PCs out.
"God blind me, he's landing right in front of us again!"
The Bjornaer maga in our party also has (or plans on) an enchantement on her talisman so that it changes form along with her.
As for nudity, if the Covenant is based in northern Europe, sauna culture will have de-stigmatised it.
sorry,
a request for magic item design assistance.
Which would be easier?
The valid guidelines for both are in TME p.107 New Guidelines for Instant Transportation errataed here.
If I understand your alternatives correctly, you trade off:
(1) the Range AC of an effect (+4 magnitudes for Range) and its complexity (+5 magnitudes for far transport);
(2) continuously having a pack follow you by means of magic, which you could control by Concentration (and Concentration rolls!), by triggering smaller effects (like Range Sight or less) repeatedly, or by trying to make the pack verrry clever.
In case (2), enchanting the pack instead of the amulet does not help you, if you need to command a distant pack repeatedly. While enchanting the pack to perform continuous clever maneuvers to follow an amulet quickly becomes a fishy question for the troupe, and at the very least requires many effects enchanted into it.
Important logistics of in-game communications between SG and players favor (1) a lot, while with (2) your character risks to become sodalis Just-where-did-I-leave-my-pack in the saga, because either continuously worrying about it or once spectacularly failing to care.
I currently imagine a 'clever' pack trying to enter the amulet wearer's room at an inn by battering down the closed blinds. 
EDIT: If the magus just wishes to enchant a pack for his clothes while scouting in heartbeast shape, he could reduce the distance over which to teleport the pack. Going with just 500 paces saves 3 magnitudes and might make (1) much more affordable.
Honestly, I feel like it doesn’t really matter; players should decide which version of events they want. If they don’t want to be naked after shapeshifting, just let them. You’re playing a powerful wizard, it’s alright. Don’t worry.
I would disagree, in the sense that I don't think one can automatically derive the mechanics of skinchanger from those of heartbeasts. For at least three reasons:
The skinchanger effect is closer to that enacted by Hermetic spellcasting than that enacted by a Heartbeast, and Hermetic spellcasting does allow minor stuff to change along.
Having a Heartbeast is generally superior to being a Skinchanger. Since they are both Minor Virtues, you might want to give Skinchanger a little slack and allow clothes to change.
For what it's worth, in old editions of Ars Magica shapeshifters' (N.B. not skinchangers', but still...) clothes and small items did explicitly change along.
I intentionally did not write "it follows", but "you can derive". That said, I consider all your arguments to the contrary quite weak.
Read again ArM5 p.48f Skinchanger: "Clothings and possessions (save the animal item) do not transform, ...". So there is no dithering at all about Skinchanger.
The Bjornaer pays for her Heartbeast with the lack of a familiar, too. In general, the Heartbeast is considered far superior to Skinchanger and Shapeshifter: see especially HoH:MC p.22 box Ringing the Changes.
You said it: "For what it is worth, ...."
So no one cared to actually read the virtue description until the topic's 17th reply. 
Actually I did.
But @lvgreen was without books and @Jank answered very quickly and politely: so I refrained from rubbing noses in the obvious.
@ezzelino wishing to disagree changed the situation.
Much to my embarrassment, I realise now that I read p48, that I had read read shapeshifter instead of skinchanger...
As LVGreen is my storyguide, if it works for the story, change the clothes. 
A SG can make up any virtue they want that isn't in the books. A creative player could pitch a new non-book virtue to a SG when making their character.
As an aside, if it has critical story spoilers write "My player's don't read" on the first post and I won't read.
So it's thanks to me that the issue was clarified 
Incidentally, note that my post still stands: I was questioning OneShot's argument, not his conclusions.
Well I can totally understand why I didn't remember that part - I totally ignored it. Because to me magic isn't stupid and so transformation magic - be it Hermetic spells or supernatural Virtues - would be capable of keeping the clothes or not as the user wants.
Its like how in Harry Potter when McGonagall and Sirius transforms its with clothes but when Peter does at the very last moment the clothes fall down to represent him going away.
So yeah, no matter what the official ruling is, I say the clothes can and should stay with the user if that is what they want the magic to do.
That shapeshifting and teleportation magic does not cover a mages clothes and accoutrements I find makes for interesting compromises and challanged for characters. In a long ago saga one of the mages was excellent at Corpus but had yet to aquire any talant at Herbam so she had to ensure any clothing worn when planning to shapechange was animal so her spells could effect it. Then she learned 7 league stride but the animal requisite meant it would be a long time before she could teleport clothes. Her solution to the problem was one of the first signs that she was going to be the most evil character I have had in a game, she made her clothes out of people which neatly avoided the animal requisite.
Every Bjornear mage I have seen or played has developed spells to shift their clothes or use illusions to cover being clothed after shapeshifting. The trope of naked lycanthropes is also somewhat traditional so I prefer to say that without the use of extra magic shapeshifting does not effect clothing. It's also a useful to keep the use of shapeshfiting magic to transport grogs and other characters in check as they they can't easily be shapeshifted along with armour and weapons
Take a look at TME p.107 box New Guidelines for Instant Transportation (errataed here), especially Instant Transportation and Requisites, for the last summary on the topic.
Not to worry Lee,
I started this thread because, as you probably now know, I needed a herald that could reach an isolated island and still look dignified and imposingly official.
While the herald is still a Skinchanger, I have made a (silent) ruling that the Transylvanian Tribunal has found a way to teach the Skinchangers in their employ to transform their clothing, but it require Vis, and a Season of work for each item of clothing, and only works for that particular Skinchanger. And then I simply gave her a Magical Mount with some hippocampus in it ancestry that could ride over to the island, while wearing barding and carrying a banner.
I think I managed to avoid dropping that spoiler. If I do say something saga-specific, I will add the warning to my players.
Though, as always, I am trying not to add stuff that can be contradicted by the official books. Just so that we are all on the same page.
The early replies were so definite, I didn't bother rechecking the Virtue description when I got the chance. Foolish me.
I'd also note that in general a Creo + Herbam/Animal etc. spell to create a temporary set of clothing when needed is often far easier than than trying to transform clothing to go along with you in your new form.
I was looking for a spell which makes clothes, and instead, I saw this comment in Magi of Hermes.
"Equipment: Alexander prefers cheap equip-ment he can discard if he decides to spend time wandering in animal form. His clothes are made entirely of animal products, so that they transform when he does."
So just have the skinchanger have full leather. If a magi wanted weapons, one could go so far as have a bone weapon. Vellum paper, bone writing implement, squid ink. A magi could take a bunch of stuff.
Alexander of Jerbiton changes shapes by MuCo(An) Hermetic spells, not by Skinchanger Virtue or such. He keeps his An and Co Forms on a similar level throughout - so casting requisites to change clothes made from animal products do not hinder his transformation spell casting.
As mentioned, post 17 advised the RAW specifically say "Clothes don't change".
I was suggesting if an adjustment of the rules is wanted, the animal product does change, is a change which is quite small.