I should also state that - yes - many manufacturers have crank down stabs, but the are NOT intended for leveling or to lift the unit. I've never seen a PUC with scissor jack type levelers. Travel trailers? Yes. Not pop ups.
I see Erwin put a post in there while I was typing, pretty much confirming what I said. Keep in mind, when you see all these travel trailers with those jack under them ---- they are not lifting a roof, like you are. By jacking...... you are putting things in a bind.
You can also use boards under the wheels. We carry a few scraps about 18" long of different thicknesses. We can take a glance at the wheel, eyeball how far off level it is, throw down a board and push the camper onto the board by hand or back it up onto it with the TV in thirty seconds or less. After a little while, you can look and determine which board or combination will give you very precise results. It's easy, and cheap (our boards were scrap, and free!)
Never level by lifting the corners. That can twist the frame. Level by raising the low side tire and the raising or lowering tongue jack. Stabilizers in the corners are there only to limit movement when you are in the trailer. Tight wheel chocks help with this too.
The first time I leveled, got the 4 foot level out, corners, front to back, side to side.. it was perfect!
2nd time, eyeballed it. Guess what...couldn't tell the difference.
Unless you've got a pool table indoors, it doesn't need to be 'that' perfect.
If the door is giving you fits, a small bottle jack under the channel where the door closes will help with any 'flexing'. Secret is to set it up to support, not lift.
I believe it was a dometic service/installation manual that said "if you can walk comfortably in your RV the refrigerator will work. The very early models ie, 1960's early 70's were a tad fussy, but not so much any more.