The reason they don't want the four wheels off the ground is two fold. One, you lose your parking brake when the rear wheels are off the ground. Two, with the entire coach in the air, all the horizontal loads on the coach turn into moment loads (bending) within the levelers; they're designed for a vertical load, not a horizontal load.
2015 Legacy SR340 360RB
2014 Jeep Wrangler Unlimited Toad
Gigi, Poppy and Sadie Lady...On the road, but not full time!