Yes boys and girls, you REALLY need to carry a spare...

My shop uses my jacks to raise the entire rv off the ground. They support it using HD jack stands.
AFAIK, the idea is to raise the rig as level as you can w/o lifting one end too high. My jacks might have an extension height limit as you lift each jack at a time, I assume its to prevent damaging the jacks at too steep an angle.