I was out fishing last night and was trolling across this wide flat. It doesnt have much structure on it and its about 5 feet deep. I was thinking, what if I were to get several plastic buckets and fill with concrete then sink them on the flat. I have no experience with this. How much concrete should go in the bucket? Would they stand upright ok? Would adding a few short PVC pipes in each one be better? Just seeing what anyone thinks.