Personally, I think he should do the liquid oxygen and liquid hydrogen fuel cells in the doors. Hydrogen on the left, oxygen on the right. He may have to use the two rear inner fender wells for more hydrogen, since the chemical mix when done uses twice as much hydrogen as oxygen (H2O). It's a LOT more environmentally friendly as well! He would get a LOT more HP out of it.
Hydrogen is lighter than air, so the truck will weigh less!
And think about Greta! She would be happier since it doesn't deplete the ozone and it makes the rainforests wetter!