Fixing design problems on a sprinter 2500 build out

Review of a camper van conversion and problems in the design
tags:
van install, insulation, mercedes sprinter, dodge promaster, ford transit, campervan, travel van, diy, vanlife, travel, adventure, thinsulate, spray foam, wool, victron, renogy, solar charge controller, solar panel, solar system, lithium, AGM, battle born, batteries, van build, 4x4, camping, espar, webasto, chinese diesel heater, lithium iron phosphate, LiFePo,