"Why not store camper on jacks?"
Three worries:
1. Wind
2. Earthquake
3. Snow load
It's not just the holding up of the TC you worry about, but the stability: the undue leverage.
This summer when working underneath the camper It was supported by the jacks as high as they would go and on dirt to boot. This put a lot of leverage on those spindly jacks. In addition, I used four dry wall jacks at an angle to support the camper for those two weeks, so the chance of wobbling from side to side or falling over were diminished. If storing the camper at the lowest ebb of the jacks, the jack leverage is greatly reduced.
In the past I used specially made saw horses and jack stands that reduced the camper ground clearance down to 36 inches but still maintaining some lift from the camper jacks. That way it was easier to get to the camper door after a 3 foot snowfall.
jefe