Here's some quick pics of the build out: Murphy bed cabinet on the port side that has 12v system and inverter below and storage above. To starboard is one of the 2 55gal aux fuel tanks. Aft to port is a removable tool cabinet that houses tools, spare parts, and some kitchen gear (induction burner, electric kettle, etc) and aft to starboard is a 12v fridge and the other fuel tank and spare tire mount. The cabinet build is with 1/2" marine ply and brass boat latch hardware, done on the cheap and to no particular standard of woodworking (I'm a welder, not a woodchipper). Bed is tri-fold memory foam type twin off amazon, think it was 90bucks. There's extra room in the mattress cabinet for pillows and blankets, and we run a 12v mattress heater off the deep cycle battery (room for two in the cabinet but only one installed right now) in the winter. Battery is connected to the trucks electrical system via a Blue Sea isolator solenoid- it charges when the truck is running but disconnects when stopped so as to not drain the truck batts, and has a 12v switch panel to control the bed heater, fan, lights, and fridge. USB ports, 12v fan, and 12v lights installed on a little shelf over the bed on the starboard side.
Benefits of a camper build this way seem to me to be that the passthrough is maintained and the central space of the box stays clear. A bed is a big thing in a small box, and when you're using the bed you're not using anything else, and vice-versa, so stowing it when not sleeping makes sense. Plans are to continue the cabinet work around the starboard side, install solar panels on the box top, and get rid of the aft fuel tank- 55 extra gallons seems to be more than enough. If anyone wants a free tank I'm in RI. Also this is my first time posting pics so please advise if I'm doing it wrong.