I stumbled across a topic about another game Garry's mod. What caught my intrest is the Zil from Spintires. You can clearly see that there is alot more interaction between you and the truck. The driver is of the truck walks in and sits behind the wheels, the doors open and close, even the bonnet. You can open/close the trailer doors and load it up with items, check for damage or oil leaks in the garage, inspect the condition of it. Tha'd be what ST mud runner needs. Topic is bellow that features the truck
https://steamcommunity.com/workshop/filedetails/?id=492608226