freezer burn is nothing but dried skin .... if your are tanning them you will have nothing to worry about. I once did an elk hide for a lady who's husband placed it in an unsealed bag for 9 years, it had a ton of freezer burn and had to be injected with a stop rot solution( I'm not sure if stop rot is still produced or not, the guy who came up with it is no longer with us due to complications substained from a slip on some ice) but if you are tanning it you could probably inject salt water if it was a bad spot ... stop rot could be brushed onto dried spots too( the elk had spots as big as a basketball, came back from tannery as fresh looking as one killed that week and tanned) ...All I needed was to get them soft enough to do a rough fleshing so I could salt dry them to send to a tannery. The tanneries deal with salt dried rock hard skins everyday( look up rehyrdration on taxidermy.net) if you are self tanning in a submersible tan then that will take care of any small freezer burnt spots
freezer burn is a simple fix. I use to laugh at guys who turned it away...I got to charge a little more and it was a easy fix esp with stop rot.
I dont post here any longer and I dang sure don't do taxidermy any longer, ( i went from full time 10-12 years or so to pt for 5-6 and I simply lost interest and the disorient have to deal with people then my freezer died while I was on a month long vaca one july. Only lost two customers fish thankfully, I offered replicas to them and I guess they said piss on it as I never heard back)
but i wanted to basically say don't let a little freezer burn scare ya.