Roger,
After 20 years with a T3 campervan I think the important features are:- (1) A full width bed, which we have achieved by having some rear cupboards that are high enough to sleep under comfortably. Under these cupboards we have three deep pull drawers at the front end of the high level unit; these drawers can be removed at night and put under the end of the bed (fold down seat). These drawers can be accessed at anytime during the day and even when the table is in place. (2) A parallel lifting pop-top, not he hinged from one end type. With the parallel lifting type you can have some fold out boards at the rear of the vehicle (stored under the roof) These boards can be used to put clothing bags etc up in the rear of the roof space when the roof is up, clearing the junk from behind the seat. (3) A decent size fridge. We have an Electrolux three way fridge that works well provided it is well ventilated and shaded. This fridge requires a minimum counter height of 800mm which is ok because if I was doing a new vehicle I would use a standard counter top height of 900 and put a drawer above the fridge. (4) A two burner gas cooker with a grill. (5) The ability to carry two spare wheels, 100 litres of water, at least 20l of spare fuel etc etc. The attached photos show some of these features.
Regards,
Dave WA