Fuel Cell- Where to mount it

You should read the NHRA rule book if you intend on racing it.

It will have a fire wall between the truck and driver

1:5 FUEL SYSTEMS
Location: All fuel tanks, lines, pumps, valves, etc. must be outside
of the driver’s compartment and within the confines of the frame
and/or steel body. Cool cans, fuel-distribution blocks, etc. must be
located at least 6 inches forward of the flywheel/bellhousing area on
rear-wheel-drive (RWD) vehicles, and on opposite side of
flywheel/housing area on front-wheel-drive (FWD) vehicles. Fuel
pressure gauge isolators, with steel braided line, may be mounted
on firewall.
Tanks: When permitted by class regulations, fuel tanks located
outside body and/or frame must be enclosed in a steel tube frame
constructed of minimum 1 1/4-inch O.D. x .058 chromoly or .118
mild steel tubing. All fuel tanks must be isolated from the driver’s
compartment by a firewall, completely sealed to prevent any fuel
from entering the driver’s compartment. All fuel tanks must have a
pressure cap and be vented outside of body. A positive-locking
screw-on fuel tank cap is mandatory on all open-bodied cars.
Insulated fuel tanks prohibited. When used, fuel cells must have a
metal box protecting the part of the fuel cell that is outside of body
lines or trunk floor, excluding hose connection area in rear. Nonmetallic
fuel cells or tanks must be grounded to frame.