Yeah thats an idea cut out a box in the floor and put the battery and electricals in there then route them to the engine bay. You could also gut out one of those storage boxes in the rear and make it into a battery tray area. If you did not put so much work into getting the gen 2 dash in I would suggest building something in the glove box area so you are not having to run your wires so far out. With your creativeness on this project so far I bet you will figure out something.

In the space you have that would make a great spot for onboard air set up.

91 Montero LS "Sandstorm", Auto, Dual Bouncy Seats, 2" Suspension lift, 2" Body Lift, GENII front IFS, 32" MT tires

89 Raider "Trailbreaker", 3.0, Auto, Dual Bouncy Seats