There are lots of alternative to waterbags, but the risk with most of them is what happens if they get pulled into the pool and sink. You can use PVC pipe filled with sand or water and antifreeze, wood boards, plastic troughs, pavers, etc. To me all the alternatives seem more costly and work then dealing with water bags. I just planned on replacing half the water bags every year and hoping only one or two would fail over the winter (I usually filled a couple of extras in anticipation when I closed the pool).
After using a trap type cover and water bags for 10 years I got a mesh safety cover, I kick myself for not doing it sooner. Other than siphoning water out of the pool a couple of times over the winter there is nothing to do. Removing water and debris from the trap cover as you know is not fun. Added bonus is the appearance and piece of mind if someone or an animal goes on the cover.