You have to be kidding! You'd get about two yards on that in the UK before you were pulled over. In any case, what does that gigantic rudder do to the handling of your bike (the motorised one!).
Handling? It's a Harley, can't make it handle any worse
As for carrying dive gear on a bike, anything's possible
It's not me, btw. I have always preferred to let the bike take the weight of any luggage. I've loaded mask, regs, bc, fins, boots, weights and a 3mm wetsuit into a mesh dive bag and strapped it onto the back seat of my bike with no problems. I use bungies and have never had it move, though ratchet straps would be more secure I suppose.