I think you might be onto something there with the fire truck idea Glen. Just had a quick look and found this:
1982 Acco Fire Truck
Already set up with the dual cab. 345 Petrol V8 so you could put it on LPG (plenty of space for tanks) and it would be cheap to run. Auto trans so easy to drive. You could strip and sell all the pump, tank and cabinets off the back and probably recoup some money. Extend the back with a beaver tail and enclose it. Have the rear door fold down to make a ramp.
It looks square and boxy like many of the trucks of the period. Paint it up right and add some chrome accents here and there and you would have a cool retro transporter.
Cheers