In my view of reality:
1.) Any site that only requires one layer of leveler blocks is considered level.
2.) The trailer will NEVER be perfectly stable, unless placed on cinder blocks, which sort of moots the point of having wheels. This is OK for some folks.
In some commercial parks you'll have a concrete pad that will be level. In state parks, you'll have a gravel site that will be almost level, not quite, and I bet they do that on purpose so water will drain away from the site.
All sorts of gadgets and tricks will "help" stable the trailer. It will never be perfect. I recently learned to put leveler blocks under the entrance steps so the rig doesn't rock when coming and going. The best and cheapest by far I have learned is just to walk softly. But I use all the store bought stuff like chocks and jacks, too. They all help a little and it adds up, I guess.
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