I have skinned many a beaver "cased" ... think it was George Wacha that sparked the idea and interest in me years ago
Here's a pic of how I hang them by the tail after doing the initial prep ... with the beaver laying on it's back on the bench ... first I cut completely around the tail freeing it. Next I split from the center of tail up through/around the vent continuing several inches above ... opening as little as needed. Next I'll cut around the ankles and twist off the hind feet. Once you reach this stage start skinning/opening each side of your incision ... freeing the hind legs, once that is achieved I attach my slip rope around the tail and hang ... now that it's hanging I continue pulling and cutting as needed ... before reaching the front feet ... cut around them and twist them off ... continue down being careful to cut ears as close to bone/skull as you can ... next is the eyes and down to lips and nose ... you're done.
Sounds like a lot of doing vs bench skinning open style ... but it really isn't ... I tend to skin mine both ways ... I think I can probably rough skin open style just a lil faster than cased ... but if you're gonna be fleshing them it sure is nice working them cased
What works for me might not work for you but you should give it a try and decide for yourself