I've kept salted hides for years before I took them to the tannery, and they still turned out fine. The trick is to keep them dry, cool and out of the sun!
~S
Both will preserve the skin by dehydration, Borax will also bug-proof it. That's why it's used in taxidermy to preserve bird skins. Once upon a time, an arsenic solution was used. Killed the bugs, and a few taxidermists too! Then in the '30s or '40s, they found that borax was just as deadly...
Be sure to remove ALL the meat and fat that you can! Putting a good handful of borax on first helps to give it some 'tooth' so it isn't so slippery, and just scrape it witha spoon. Don't forget to work on the tail butt if you are including that ! Then another good dosing of borax on the...