Just leave the AC on all the time. The effect on fuel economy is negligible, you'll be less likely to have to regas it in the future...and it will keep the glass clear in the wet.
Must say I'm jealous of those who get to own these cars in Scotland or Wales (well, maybe not Wales now

). Down here in the south east, the opportunity for decent driving roads which aren't congested are few and far between...would love to spend a couple of days mooching around the Highlands.
I think you'll be okay. I had to take apart a GT86 mirror once and even though it's electric it's mounted on a spring pivot, I guess so that if it takes a whack and gets folded in by force it shouldn't damage the mechanism.