Bowti wrote:
Save yourself a lot of money and grief and buy hard sided kayaks or a canoe. One problem with inflatables besides puncture, is they are hard to regulate as far as air pressure. Leave them in the sun and you exceed recommended pressure, put them in cold water and they become under inflated and float like a anchor. Forget about covering any distance with them, as they push the water instead of gliding over the top. If you want to float down a river fine, but don't try going against any current. Things are much better with the higher priced ones, but I think you would be much happier with one that is more versatile.
As for carrying, this seem to be very popular way. Loading and unloading is easy.

I guess since you say you see a lot of people doing that then it must be legal. But, I don't know. Seems a little iffy to me. Sticks out further then the bumper and blocks your vision upward. Can you even see stop lights with that mounted like that? I don't think my local police would like that. I'm not sure what ticket they would write you but, they would think of one.