Lumber, lots of lumber, 2x4's / 2x6's / 2x8's / 4x4's / 4x6's. Been dragging these things around for years and years. They came out of an old barn on my in-laws farm, probably over 100 years old when I got them and that was 40 years ago. Most had to cut with a chain saw. I paint them different colors when the paint wears off. I've replaced several of the 2x's as that was simply treated lumber. But those original posts from the barn have lasted and been used relentless and still show no signs of cracking or any type of failure. Yes.... lumber is heavy!
With lumber, you never have to worry about it failing. But it does take space to transport it. But can not be beat for stability under the camper, leveling, or to keep from sinking in the ground.
Long boards work well on soft ground, like sand and grass. I carry those in the bed of the pick-up truck.
Why so much lumber? Because, sometimes you just never know when you'll need more than you anticipated. Travel East of the Mississippi River, you are going to run into campgrounds eventually that are way out of level! Always be prepared if you actually travel!
