Have bought the Skymaster fuel tanks for their Viper 2.0m. The main tank is 2200mls and would sit forward of the mid section bulkhead. It is beautifully formed to fit in between the air intake tunnels in the centre of the fuselage.

Thoughts are to run the two FEJ tanks in parallel, and feed into the main tank 2200mls, then through the UAT. Probably just keep the fuel load down to the 4000mls mark.