I feel as though it should be mentioned, as to not be overlooked. If you are using or intend to use DT foam board for you swappable, leaving paper on as a function of structural integrity.....it would be , well, ill advised. DT foam board paper backing does not hold up well to any kind of moisture. Sure you could laminate with packing tape but of you leave any pin hole or gap for water to work in its all over. Better foam options out there for "wet" work.
Yeah, it's pretty much a Nutball, or the Nutball is pretty much a Snowball. The point is, Build a Snowball but instead of using the solid foam pylon, mount your Swap-able powerpod on the top of the Snowball AND go fly.
If you just put the floats on your Snowball your pod will be in the water. Well lets face facts, the whole thing is going to be in the water so if Aqua fying is in your future, just build the foam pylon. Gonna fly on snow, go the swapable.
I just built a Ski baby, Blu-baby on skis, and all I did was bend 2 pieces of 2x14" FFF, skin down to form skis, then added a rear wire gear to support the back end, and 1/8" dowels between the skis to add strength. To attach them, I simply attached rubber bands around the ski struts to the wing dowels. I can't post pics right now, But I can explain it a little better later.
It will fly fine, It will land fine. If you don't remove all the snow or waterproof the paper covering you'll have a mess when the snow melts on your plane. The only downside of flying a paper airplane is you have to get it waterproof or keep it away from any source of water.