I'm not completely convinced that magical senses aren't enough to overcome the Limit of Arcane Connections. The description of To See As Through a Plethron Distant describes it as not working with Sight range spells, not as not allowing the target to be sensed. It does go on the extrapolate that the reason for this is that the recreated species don't bear sufficient connection to the original target to support casting spells against them, but whilst that could be read to mean a species has to be natural, I think it doesn't rule out an unnatural species emitted directly by the target.
The very similar (if not the same) issue of targetting spells detected by Intellego Vim magical senses is possible (for example, See the Light of Magic on page 83 of Hermetic Projects).
The Flambeau section on fighting invisible opponents is less useful than I'd hoped - it says you cannot be targeted by spells unless the caster has an arcane connection or is able to locate them, but then doesn't list even Second Sight amongst the ways to locate them.
On a less "wording of the Rules" point, I don't like the idea which this seems to imply that if you're not lucky enough to have Second Sight (or equivalent virtue) you're completely out of luck directly targetting invisible things.