IMO, you are wasting materials and labor putting anything for gills and redears on any bottom but sand or pea gravel. If the attractors for gills/redears are placed in a minimum of 4-5' at summer pool and out of any navigation areas, they should be fine. The short stakes in that water depth are probably not going to attract crappie or bass in any great numbers but should be a mecca for panfish. Pour a white PVC stake in a small bucket of sacrete and drop it right in the middle of the series of beds and that should be all that's going to be needed as long as the bed locations are documented. A series of no less than 4 beds at each location a few yards apart should be considered.The grid beds would work great for redears. Some of the most effective redear spots I've seen over the years were short stakes driven into sandy bottom at 4 corners then limbs of willow or oak tied horizontally to the corners forming a grid about a foot off the bottom that was high and dry at winter pool..