I can't help but laugh at this - the OP said he has a "nice breathable cover" and somehow that got interpolated to mean a tarp.
As far as storage, I lower my Arctic Fox on to 3 6x6 timbers, with additional wood stacked on top. Arctic Fox (same company as Wolf Creek) recommends supporting the weight at 3 points if you lower it down and don't want the jacks supporting all the weight.
I wouldn't recommend screws jacks at the corners, and definitely not the plywood criss cross "X" things, since AD and Wolf Creeks campers don't have a sold bottom. The camper needs supported at the outside edges.