Water Level while pool is closed

[wal81]

This is my first year with a pool. The pool is closed with safety cover on. At the time of closing, water level was dropped to below skimmer, lines were blown, and gizmos were installed. We've had 5 inches of rain in the past few weeks. The water is collecting a little bit in the middle of the cover. The water level in the pool has come up to nearly halfway up the skimmer and the lapping over the top step (which is where we keep the water level in the summer).

What to do?

What is the ideal water level during the winter months? Should I be concerned about having water in the skimmer, or does the gizmo take care of issues there? Or should I just be concerned about keeping it below the liner?

Thanks!