Here is my idea for a Rock Crawler rig toy. This is my rock crawler that started out as a 1984 Bronco 2. Rock crawling is a world wide activity. Kids just fall in love with these rugged very animated trucks. That include large knobby tires, usually short wheel bases and round tube linked suspensions. Mine has a 4 link front and 4 link rear that holds the large axles in place but lets them articulate different angles while the body tries to stay level. Also for the most part they have coil over shocks. I would think that if this toy was made it would have to have the large knobby tires with actual springs that are made to go over the shocks. For example if one was to push down on the toy truck it would actually move up and down.
Here is a pic of the linked suspension along with the coil over shocks. Also the truck has an interior roll cage along with an outer cage which is commonly called an "exo cage". This helps in protecting the body in case of roll over while rock climbing. Notice how the axles front and rear are articulating while the body stays mostly level. This is a trait of these rock crawlers.