1967 StarCraft Holiday, i have a Tempo 12 gallon Polythylene fuel tank that is located under my boats closed bow. Refueling is difficult. I want to install a Perko combination gas fill and tank vent near the front of the boat and run a gas fill hose to my Perko 12 gallon tank.Question is ...is there a replacement fuel tank cap..( adapter ) that will allow me to connect the fuel line hose to my Tempo 12 gallon tank.Has anyone heard of this being done???