My preference is to just leave the buckets and drop them with the cover.....my line of thinking is that the hedge apple/Osage Orange or plastic cover will last for generations/forever??
I do not want to take a chance that the base of my entire build will disintegrate and fail. Over time bare concrete will collapse and I just don't want to chance it.
We have a local bakery that will give you whatever you want just to get rid of them.