Of course I never raise the rear wheels, but the DW doesn't like my front end wheels off the ground unsupported so I use blocking with wood under them. What really helped me with my leveling jacks is I bought a 8' long Douglas Fir Beam (6" X 6") I made 3 two foot cuts with a chainsaw (which gave me 4 two foot pieces). I take the 4 pieces with me if I'm going to a place where I know the front end of the coach needs to be raised up. This 6" X 6" beam that I paid $8.00 for from a local lumber yard has given my jacks an extra 6" in length. I haven't had my front wheels off the ground since.