My trailer is level front to back but I have it tilted a few degrees to the side opposite the door and awning. This allows my air conditioner run off go to the back side of the roof to run off...
On my POPUP I only need to get it level from end to end (FRONT to BACK) so that my door will open freely.
I have a bubble affixed to the frame here to show when the door is level enough to open.
I run my fridge alot when going down the road and it seems NOT to be bothered by any of this being our of level that you hear about. Runs just fine for me. We like to fire up the fridge on 12VDC when we get within a couple of hours of arriving at the camp site to get it started to being cooled down. We only run a couple of days out of the fridge for meals. Usually a WALMART or FOOD LION close by to buy fresh food from...
Roy Ken