Today I made a little progress. I bought 2, 30 oz aluminum fuel bottles from REI. My local Bates Discount Cycle supplied this 3/8 pipe thread petcock for $14, and Turner hardware, the best hardware store on the planet, had a tap and die plus a brass lock nut. This is what I ended up with. I'm going to use 2 of these bottles mounted to a bottle cage mounted to the seat post for fuel tanks.