That's a good question. Unfortunately, we don't have many truck camper owners on here, but there are some.
I'm assuming you do have jacks on it, right?
I've seen all sorts of storage methods, but unfortunately most people just leave them on the jacks long term.
Saw horses do seem to work pretty good, and I've also seen people pile up a bunch of pallets and set the camper down on those. They usually do enough so they aren't setting the camper down very far, and then they still use the jacks as side support.
Then again, I've seen a fair number (in craigslist ads this is) who store it on a flatbed trailer. I think quite a few pull them around like that too.
2007 T-286SR Cherry/Granola, #6236, original owner, current mileage: 9467.8 (as of 5/26/19)
1997 T-2653 Blue Denim, #5471
1979 12 1/2' MC, Beige & Avocado, #4639
Past Sunlines: '97 T-2653 #5089, '94 T-2251, '86 T-1550, '94 T-2363, '98 T-270SR