Billy ,
On mine I am never gonna use it to haul Coal or Feed , so I already have a Handmade tool box that weighs in at close to 200lb and I am mounting a fuel cell directly over the axle in the bed and mounting the battery inside the tool box to get more weight towards the rear.
sounds like you are like me and want it to RUN ...so you could mount your spare under the bed and a fuel cell in the bed hope these ideas help.
Tim


1952 Chevy Shortbed

Photos in Photobucket

If It Aint Broke Fix It Till It Is!