Leveling a Pop Up
One of the most mis-understood things about setting up a pop up is getting it level. If your pop up isn't level you may run into issues like the door not fitting right, the refrigerator won't stay lit, and other issues. Here's a few thoughts-
The first thing you need to do to get a camper level is to use a carpenter's level and check the bubble. Eyeballing it isn't close enough. I suggest setting up on the most level spot you can find, and using the carpenter's level to see where you're at. Place the level on a flat surface of the camper, side to side should be checked first. If one side is low add blocks or wood planks under the tire by driving up onto them. Once you get side to side level, use the tongue jack to level front to back. Once you know the camper is level it will be to your advantage to buy and install bubble levels on the side and front of your camper. That way when you pull in it's easy to check where level is at.
Above is a BAL Leveler. Easy to use to level a camper side to side without having to pull forward and backward to put blocks or wood under a tire. Once you set the camper where you want it the BAL simply slides under the tire and you crank it up to where you are level. The only trick to the BAL is you have to keep the screw well greased or it will bind.
You can buy a pizza bag or use a short piece of pool noodle to cover the screw to keep grease from spreading all over.
Another option to level is Lynx Blocks. These are like Lego's and stack together, locking in place. You use as many as needed to raise the low side to level, building them up like a ramp. The problem with these is you have to know how many will level your camper, or you'll be pulling the camper on and off several times.
And then you can also use wood planks. Some like to build wood planks similar to Lynx Blocks, but again it's the knowing how high to stack them to get level besides having to move the camper every time to add or take away.