I've been doing some research and got the co to send me the fitting instructions for the F250 tank (model tr57) which the PO had put in my truck.
The tank is made as 2 tanks with linking hoses. The rear section is the larger with the top section of the tank extending over the drive shaft. The linked tanks hold 270Ltrs of fuel.
I looks like I should be able to just drop the front section to get to the stock fuel pick-up, which is reuse, in order to do the hutch mod. While I'm doing that I'm going to fit one of their fuel transfer pumps with a water seperator/fine filter after the pump and a coarse in-line filter before the transfer pump. The other trick is to loose the stock fuel-line push fittings between the fuel pick-up and stock fuel pump as they allow air to be sucked in, and replace each of them with two 180 degree off-set hose clamps.