Wasn't as big as you'd think, it took up the space a bed tool box would have.
I had no problems with it.
In my case, a 89 F250, 7.3 liter IDI diesel, I was making my own fuel, and could carry 76+19+19 onboard, had an effective range of 1,600miles.
I was using the factory camshaft operated lift pump. Since the two factory tanks used a 6port Pollack valve, I added two, 3 way valves from Mcmaster carr... (bout $30 a peice).
This was a diesel, where I needed the second valve for a return line, I'd assume with a gas burner, you'd only need 1 valve.

I don't know the legality regarding gasoline storage.

best of luck,
Drew