Putting Ideas on paper

Just doing out some rough sketches of what i think ill need in terms of space etc....

Trying to figure out where to put, leisure battery, heater for overnight sleeping, going to make a pod unit for the back that I can wheel in and out when Im heading off, this will have, cooker, sink, fridge, sink waste, water supply tank for sink, water pump, gas bottle for stove, storge space for pot and pans cup plates etc, some storage space for dry food, tin food etc...

should be able to wheel this into the back and lock the wheels and maybe have brackets I can fix to partition wall for extra stability...will have one more pod unit to store fold up chairs small round table...

In the front section will be a rock and roll bed / tool box / bench / area to house leisure battery and gas heater ? looking at putting in a screen mounted to the ceiling over the sliding door for watching dvds etc and a few speakers in the walls, plug in playstation for rainy day or evening use...

thinking of reversing camera with 2 lights mounted over back door that can be switched on from the cab to light up rear of van when reversing and or loading at night...

Loading ramp 2.4m x 0,75m will be stored under the floor snf pulled out when needed...

Do I need a gas type heater when I have a leisure battery ?

So Im now looking at the gas type heater for in under the bench / bed with stat wired to leisure battery, this will be used to heat the sleeping area, I might take a tee off the output pipe and run a feed into the back through the partition wall or else put a vent in the partition wall to allow some heat to flow back there, this will be a garage space and kitchen dining area only, the main area i want to have the heat in would be the sleeping area...have marked on the plans where I think each part should go...