Box Truck
A box truck, like a step van, provides a large cubic space for an easy build.
Pro & Con
Pro:
Large living space
Square shape easy to modify
Easy solar mounting
Passthrough (on some vehicles)
Space under truck to hang tanks, storage boxes, etc.
Con:
Low MPG
Insurance may be difficult to obtain
May be difficult to find repair shops
GWVR may require stopping at weigh stations in some jurisdictions
Floor is above rear wheel (no wheel wells) so more difficulty getting in and out
Resources