ok I think I just came up with something you guys have ALL overlooked, it might not be a big problem, but I think it's sorta substantial. ok, I know nothing about skating, but I do know skate wheels aren't too big. and if you look at mountain boards, they have huge-ass inflatable wheels (I think, I've never seen one in person, and I'm too lazy to lok up a pic). the weight of the wheels and stuff is ok with a board because you have both of your legs to lift in when in the air, but with skis, you're using one leg for each ski, so you'd need more strength. I know you said they'd be lightweight, but I still can't really see it. and if you used little tiny skate wheels, landings would be hard, like no cushioning, and depending on what your design is like, I have no clue really as to what your wheel setup would be like, the wheels could get like jammed sorta with dirt or grass clumps. this may not make any sense ot any of you, but try and visualize it and you might realize what I mean.