The box on my hard floor campertrailer doesn't do what I want. Fridge and more. Looking at one I hired (Far and Wide) had a pod for fridge and jerrys/gas on the other side. (the batteries were inside)

I will have fridge and battery in my box and was considering a enclosed compartment for the jerry/gas bottles. The current box is smaller in height and width than the trailer. I think I might make it taller up to the boat racks height. Was tossing up having a side opening with shelfs to use as a pantry allowing a little easier cooking on the run but think this might test water/dust proofing needs a little much. Will put the drawings/desing up as I get it done.
Has anyone designed a perfect camper tailer box?