Well like Forrest Gump said, since you've gone this far, might as well go a little farther make them look like floats, and include the little step on the bottom that helps the potoon break the surface tension of the water. Just a little zig zag up behind the wheel well. It may be a little cartoonish looking, but painted properly to match everything else, I think it will look OK. I'm sure you'll be making them removable and can always take them off or build different ones.
Type at you later,
Dan McEntee