I used to travel with two, behind the seat in the truck and then when camped I would attach them at the front of the camper, lower them, and put just a little pressure on them, to stabilize the camper from rocking around.
Eventually I got better rear leaf springs on the truck, to carry the camper better, and I don't need the jacks anymore when we're camped. There is no wiggle of the camper when we're inside.