Installing a swingset/play area

[BrianG]

My wife went out and got a large swingset/playarea for the kids. It arrived the other day in a double length 700lb pallet and now I get the "joy" of putting the thing together.

My yard is not very level, so I did my best to level the area. I didn't want to use bricks or cement to lift the low areas because it would create places for kids to hurt themselves if they fall on them, and the wife wants to be able to maybe move/disassemble the play set in the future.

So, I "wisely" decided to dig out the high spots (~5" max) instead. However, I obviously have these shallow holes where rain water can accumulate and possibly rust the bottoms of the metal poles (they are powder coated, but not sure how well the insides are covered). I didn't think of that until the thing was about half put together. Grrr. Since pouring cement is not an option (being permanent), is there some kind of rubbery material I can pour into the hole to fill it that will keep the pole bottoms from rusting, yet is fairly easy to remove if we decide to move/disassemble it? Something with the consistency of hotglue would be perfect, but that's a LOT of hot glue, lol.