Locking Gas Caps

It has the 4 vent tubes coming off the gas tank that go up into the "extra trunk tube". Then one vent tube goes to the valve cover breather. No charcoal canister. I'm seeing some locking gas caps that have thicker gaskets. It might take up the clearance. I may try one of those. I don't understand what the difference is on the gas caps. Mine has a simple one way suction valve. Like what happens if you use the wrong cap?