Honda euX000i Fuel Extender

A lot of people seem to have and love their extra capacity generator fuel tanks. Most seem to be built using an outboard boat motor fuel tank. I would think the deciding factor on whether an extended run setup is worthwhile would revolve around the Honda fuel cap. If the cap leaks air, it won't be able to suck fuel from the tank.

Did you have a specific kit or tank you were considering? Could you link it so we could take a look?
Thanks