this is an old thread with pics of my truck about half way thru
i made it from aluminum sheet of varying thicknesses ie external 6mm internal 2mm with internal box section frame with a standard fiberglass canopy on top
checklist was
hard top for better dust and water sealing also can be slept in a without people knowing you are inside (rest stop or carpark camping)
full size double bed ( that did not have to be cleared at night) to hop in
full vision out the back ( windows not bulkheads)
enough storage for tools spares etc under tray not in camper (incase camper is removed) flatbed mode
aprox 280 ltrs of fuel no jerrys alowed
fridge
at least 30 ltrs of drinking water
kitchen easily accessed from foot path without unpacking anything
has to be very strong and light
can be removed fully packed so ready to go in 15 mins
this is what i came up with

on the creb track

full size double bed

kitchen

storage for tools and spares under tray

driving from one island to another while in the pacific

top section removed flat bed mode still has all tools and recovery gear inside tray

large under floor fuel tank

under construction showing integral water tank

underside of tray during construction

more storage showing compressor and rear winch compartment