72 Demon fuel fill vent tube ideas?

I gotta tell you guys. I would not in the least be afraid to try this. But if the tank has the SINGLE vent into the tank, this means the vapor separator is integral. I would simply fab a tube/ hose off that tank fitting, run it up into the trunk beside the filler just like the early vent, "U" bend up by the top and (to keep it high and prevent siphon) run it down into "near the top" of the wheel well from the trunk.

You want to end it up high to prevent siphon. The reason the fill tube type vent can be "so low" is that the fill tube itself forms a vacuum break. Only way it can siphon is if the tank is so full that the fuel is clear up in the filler.