Originally Posted by bikendan
be careful about adding jacks. if you have an ultra-lite frame, you could damage the frame.
Indeed. They should never be placed under the camper frame without some modification to distribute the load, and should not be used to try and lift the camper. Stabilize only with moderate pressure, just as with the rear jacks.
Campers with the rubber torsion axles have a subframe mounted under the "I-beams" of the camper frame, and that is what any extra jacks should be mounted to. Ideally, one would mount them in the center, to distribute the load, and considerable jacking force could be used there, but they would be difficult to access. The second best place would be at the front of the subframe, but much less jacking force would be desirable, as the load would not be as well-distributed.
Anyone with an ultralight frame should take a really good look at it, and that would be enough to convince you to be careful with it.