You don't need to strain your jack to hold either the front or back of the camper with one jack. My jacks are rated at close to 3000# each and the entire camper is about 4000#. It is not physically possible or certainly feasible to exceed the jack capacity. That would mean almost the entire weight of the camper on one jack. All that is needed is a jack capacity that will support about half of the camper's weight. Nor is it necessary to jack up the camper at some extreme angle that will strain the jacks. Just a few inches is all that is needed.
Anyway this whole argument is silly. There should be no problem putting some pallets or other supports under the camper so that the bad jack can be disengaged and replaced. In fact it is not necessary to have any of the weight on any of the jacks. The entire weight of the camper can be supported by supports under the floor of the camper.
