What are the key features of a Off-Road camper?

What things have to be modified to make a TD/TTT off-road?
Frame differences?
Axle, hubs, leafs or struts?
Cabin modifications?
Height clarences?
Tongue? Hitch, Ball?
Anything else important?
Frame differences?
Axle, hubs, leafs or struts?
Cabin modifications?
Height clarences?
Tongue? Hitch, Ball?
Anything else important?