with reference to thedjjack who got me thinking, I started to convert my ride last year in June, starting from a freshly acquired petrol van.
Many things from my old L300 Diesel bus, including 7 years of camper experience, went into the project.
It just fits our current requirements nicely. We use the bus for leisure trips only (no daily driver, no winter use). When my wife and me go places with our son (14) he lives inside the van and we occupy our Eezi-Awn roof tent. Living mainly outside then, it was sometimes hard to get to our stuff while our son was still sleeping on top of it. Plus we wanted the luxury of our own toilet and changing room on board, without sending all others out, as we sometimes camp on dedicated campervan parking spots in cities, where there is no toilet available (and no other options to go).
Sometimes I am lucky enough to get away with a twosome weekend, where we can leave the roof tent at home, then the van sleeps 2 persons, and all the additional space inside is just great. Typically this is not in summer, so I am planning to fit a woodburner stove later on.
But so far this is what I have done, we tested it in a 4 week summer trip down the coast of Croatia and did fine:


Basically I made the complete space behind the 2nd row seat bench into a slide-out, which houses luggage and has room for a portable toilet, or to dress or wash. The freed up space inside makes room for a vehicle-wide queen size bed (we use inflatable matresses for that).
This is it with my son, using only half the bed:
There is a build report on my website:
http://www.motorang.com/L300/L300_innenausbau_neu.htm
Thanks to Felix (dinoevo) and David (thedjjack) for answering nosy questions!
Andy