^I wouldn't be so sure of that man- this year I broke my binding on my park skis in Tignes rented some volkl walls which had never been ridden, centre-mounted. I guess the guy in the shop is kinda a friend of a friend but still- sure they won't have non-symettrical centremounted skis (but i think that's retarded anyway), but it shows that if they stock something like walls and if you can speak french and explain exactly what you want, then it's possible. I guess what I mean is that if they do have good centred park skis, they'll most likely only have a limited number, so they might not want to rent them to people that either don't try to speak french, or look like a gaper.
but yeah, there will be plenty of places at any resort to rent.