This whole thread seems strange. The OP has asked for information on using the camper while on the truck. It is designed for that. The bigger issue is using the camper while off the truck and supported by the jacks.
First to do this, you really need to have the camper on a paved or other very firm, flat surface. Even then you should use blocks under the jacks to distribute the weight.
Next I would check with the manufacturer to be sure the camper is designed for use while on the jacks. Is the floor built for people walking around without any support underneath? At a minimum, you need to lower the camper as much as possible. Often that will still be several feet high with a lot of sway and strain on the jacks. You might want to consider carrying a stack of pallets or other support for the floor. When checking with the manufacturer you should also ask about use of the slide. That will further strain the jacks on that side of the camper.
In theory my camper is designed for use while on the jacks. Even so I make sure the tanks are empty and avoid getting into the camper until I have it further supported with pallet racks under the floor. I keep about half the weight on the stack of pallets and about half on the jacks. If a jack fails the pallets will take up the weight and the camper will not tilt. A few years ago, I had a jack bind up and fail. I was easily able to transfer the weight to the pallet and other jacks and to then replace the failed jack.
Good luck continuing to use the camper without support of the truck bed. If you don't want to carry a stack of pallets across country at least try to find them or something else suitable at your destination.