Foam mats will get the job done. Ghostguy posted a Cabelas version, Fishin Hole sells the HT one.
https://www.thefishinhole.com/index....OVER/&se=28740
Or make your own from some sort of foam. All you need to do is cut a hole just big enough in the center and a slot from one side.
Or buy round insulated tip ups that cover the hole.