In reply to wallym:
There's a facebook group called 'Vehicles for sale or wanted for conversion to living, travelling etc..' which you might find helpful, I think there's bound to be people who have done or are doing what you're thinking about as it's quite an international group.
I'd perhaps be tempted to think of a 'stealth' version as I think it would be less of a target for thieves, as a law abiding person I always think there's probably lots of things in camper vans as people won't always be wanting to take things like their laptop etc with them when out and about.
You could perhaps have your sofa or sofa/bed at the front seats end so light goes into where you sit, and have a roof window above it too with a blind to keep out the heat, and have windows in the back of the van with blinds on for privacy when you're sleeping, so the environment inside is still nice and airy?
I've walked past the odd 'stealth' van with a little wood burning stove flu poking out the top, it looks weird to see wood smoke coming out the top of a van.
Post edited at 11:53