The picture that you posted shows it in the lock for the helmet lock, so I can't comment on how it looks in the gas door or the cubby lock.

I made two such keys with the knobs, one for the cubby/gas cap (it normally stays in the cubby lock and I only move it to the gas door when gassing upo) and one for the saddlebag lock. I measured them and tried them to get them just the perfect length so that the knob fits nicely and looks built-in. After that, I did the epoxy to make the key solid in the knob.