I think you are doing all that can be done. Screens fine enough to get the slivers of glass would have to be vibratory to separate all the glass. Use the Landscape rake to windrow it then pick up all that dirt and bury it below the freeze zone(18" deep should do it) which should be pretty shallow in SE Texas. Let the rake dig down a bit and gather it all up. You may still have some hand picking to do.
