My opinion...remember where ya got it!
Front wheels off the ground is not an issue. However it makes me uneasy so I use Lynx Levelers. Rear wheels off the ground is a nogo for me. That is what "locks" the camper and keeps if from rolling. YMMV
Just as an added note, I have noticed that I can quite often keep the camper closer to the ground by using the manual mode rather than the automatic mode.