Along the same vein of "it doesn't matter what you fly" I am down at the strip today filling in rabbit holes and parked up in one corner are 4 micro lights (2 fixed wing and 2 weight shift) on the other side is a guy flying an RC piper cub, and down the end is another guy familiarizing himself with his para kite thingy (the one you strap a fan on your back). So no rules on where the wheel has to be or even have a wheel at all, it's whatever floats your boat that matters.