That's exactly what I did when I used to have an AGP. I didn't use a Gizmo in the skimmer box because the hose wasn't connected, so no water/ice could build up in there. I just covered the top of the skimmer to keep some water and all debris out. The skimmer was wet inside, but no ice could build up. Water would always drain out of the open bottom, so no freeze issue. We were on well water, and I didn't want to lower the water level in the fall.
I made sure to get the winter cover secured under the top ledge with the red ratcheted cord, and I also used cover clips to keep the cover from flapping in the wind. We had a composite deck around about 1/3 of the pool, and I was able to remove 1 board per section that ran parallel to the pool to get the cover under the deck. Then I would reinstall that board and get a tight fit with the cover. Hopefully, if you have a deck, your boards run parallel and not perpendicular, and you can get the cover under the deck. No water bags on the deck. In the spring, I would always have clear water, just a couple worms found their way in. Just make sure the birds don't use the water on the cover as a bird bath, as they could puncture the cover.