To get level in a campground, do whatever it takes to get the floor of the RV level, front to rear and side to side.
We usually worry about side to side first. Put the trailer about where you think you want to park it, then use a 4' carpenter's level to see if the floor is level side to side. If it's not level, then use lumber or Lynx blocks or something to put under the trailer tires to get it level. Whether you put the levelers under one axle or both doesn't matter as long as the floor of the trailer winds up level.
After you are level side to side, install wheel chocks to be sure the trailer stays where you parked it. Here's mine:
Ultra-Fab Chock and Lock Wheel Stabilizers for Tandem-Axle Trailers and RVs - Qty 2 Ultra-Fab Products Wheel Chocks UF21-001070
Then lower the adjustable part of the landing gear and get both feet the same distance from whatever the landing gear will be sitting on. My 5er landing gear "feet" were adjustable enough that I rarely needed to use Lynx levelers under one of the landing gear feet to make both landing gear feet the same distance from surface they will be resting on.
Then lower the power landing gear to raise the kingpin off the hitch, and disconnect the trailer from the tow vehicle, and move the tow vehicle out of the way. Then use the 5er's power landing gear to level the trailer front to rear.
After it is level in both directions, then put down the stabilizers and get them snug but not too tight. NEVER
use the stabilizer jacks to level the trailer - get the trailer level before you tighten the stabilizers.