Just as a word of caution . I had personal experience when my friends tc tipped over and crushed his shed.
If i were going to unload a used unit for the first time, the first thing i would check to see is...
Check the lag screws where the jacks are mounted to the camper. If they show rust, this could mean that water seeped into the corners of the camper rotting the wood in those corners.
I checked mine by backing them out 1/2" , one at a time, to see if the threads were rusted. Just make sure the camper is solid where the jacks are mounted.
Campers have fallen over when jacks rip off the corners because of rotted wood, not visible to the eye, can't support it .
Those screws should be cauked if they aren't already.
Once you determine the unit is solid, getting it back on takes more time because you must be straight as you back under the camper. I find it easier to do myself than use a spotter.
The front of the camper should be raised a little higher than the rear...2-3" as you load and unload. Make sure you dont hit the front jacks, adjust your sideview mirrors.
loading a truck camper-video I would support an AF while off the truck. To prevent basement stress from a heavy freshwater tank.
If you choose to do that, make sure the supports are wide enough to support he load . Otherwise you will cave in the bottom of the camper. The vertical sides of the camper are the strong points.
This is just an example of what someone made. Saw horses or blocks with cross members could be used as long as they are wider than the bottom of the camper for support.
http://www.jaysnest.net/x-braces.htmMake sure the ground is solid under the jack feet. Soft ground is the enemy. I would use some square boards under the feet.
Take it slow, you'll find it easier the more you do it .