I was thinking of getting an ex-police Sprinter for conversion with the mind-set that it's already insulated, most have a webasto heater installed and has roof-vents etc.. I'm sure it's been done before I'd like to hear about the pros n cons..
Brilliant!You could always try before you buy.....get arrested, and sit in the back, whilst there check out engine noise & performance, suspension, and sound proofing,the sat nav will have every police station, law court, possibly prison set up as POI's , then en route just shout at the top of your voice....it wasnt me!, you have the wrong man!......check soundproofing for echoes other than that I would do as others have said thus far, if its in good mechanical nick, arrest the idea, and go for it.
I think you might need to do something with the panelling anyway, so look at it as a blank canvasI'm hoping for a 516 or similar so weight shouldnt be a problem. Sourcing one might be though. I might have a problem running pipes and additional electrics as I'd have to get behind the panelling.