Thank you so much for your replies! Yeah, I'm planning my first-aid and "foot maintenance" stuff (Clippers, nail file, cold cream). I'm going to bring more blister-plasters than I think I'll need, definitely, and stuff like extra shoelaces and duct tape!

I think the actual exertion won't be that high, it's a themed trip called the Mercantour Panoramic, so we'll be seeing a lot of sights! For one thing, there's a valley, Vallée des Merveilles, where there are about 40000 ancient stone carvings. On the rocks that is, not statues. I imagine that day will be lighter on the distance!