Levelling blocks for camper on driveway with 2 degree grade

I use concrete blocks and 4X4s to rest it on. I have a few 2X6 to make up for unlevel driveways. if they are Hydraulic jacks you definatly cannot leave the camper sitting on them for extended periods of time. if they are screw jacks the jacks may handle it, depending what type it is (acme or ball screw) I wouldn't leave either sitting on the legs for long periods of time myself I would still build some sort of base under it and lower it down to take the weight off the jacks.