2 thoughts on your desire to access the fridge/cooler from outside:
1) The closer the fridge is to the back of the truck the more the stuff in it will be subjected to bumps and other motions. Think "back of the bus". We had a few "fridge surprises" that got me to move the fridge to the front of the camper. No more issues with stuff spread out all over the inside of the truck or fridge since that move was made
2) Cooler on the outside.... no bears or such where you camp?
Vic