Are you going off improve roads? Many rental contracts don’t allow.
Years ago I rented a truck for a month and used it for work off road. IIRC the guy sold used cars as well and had the rental as a side thing.
The truck I got was pretty nice but had a few scratches on it. I told him I would be off in the brush and would pay him extra if need be. I returned it full of brush marks on the side and a helper tore the seat with a screwdriver in his pocket.
The guy didn’t charge me anything extra!