We have a 1999 Bigfoot C25 10.6, so it's a big camper. We set down 4 stacks of cinder blocks, one near each corner. Each stack is made from 3 blocks, 2 on the bottom, and then the 3rd block running crosswise to the other 2. We place a couple 2"x8" across the stacks, one across the front of the camper, and a second across the back. We set the camper down on that. We keep the jacks lowered touching the ground, but without having them carry much weight. That arrangement seems to work fine.
We've tried various covers over the years. The Adco covers are OK, but the problem we have is they seldom last much past their warranty date. Seems like we can get about 2 years out of a cover, and they aren't particularly cheap. Over time we've become less and less picky about keeping it covered, so at this point we don't bother. The camper does look like it's been out in the sun, but not really too bad considering it's age.