I know I'm a little late on this but yeah, I ran wedge chassis with a 583 rotax on the water for years around central Alberta. Worked great was awesome fun. I've been looking for another one to turn into a water crosser.
I always thought Snowmobiles were meant for Snow. lol we have a local nut ball that drives his Yellow stuff on the Mcleod river all the time., see if can the video I have of him