Clint....Nice score.Hope you got em cheap enough.I use my buffalo hides to sleep on rendezvousing.Sleep under them too.A tannery north of me does them for $10.00 a sq.ft.They'll shave them to before of course.
You can go ahead and try to thin that hide with a sander of any kind...Good luck!!Go ahead and try. Even 60 grit on an area the size of a foot square will take you hours and many many many sheets of sandpaper.More then you've ever bought in your life.Dried rawhide is tough tough tough.It needs to be shaved thinner when it's green.Gotta get it fleshed first though.Never used a power wash to flesh before because it does'nt do a good job.That wo'nt get the membrane off.I'll garauntee ya.If your gonna tan it yourself.You've gotta get the membrane off for your chemical to penetrate.It needs to be pickled first too.Powerwash might get flesh and fat some though.Did use one to clean it up good first before lacing it into a frame though on the hair side.That's why getting it shaved to an overall same thickness does the whole shooting match at once.Fleshing and thinning.You can but a flesher shaver from a taxidermy supply center but that'll cost too.A lot.Talking from at least a half dozen experiences working with hides of this size and nature.If you chemically tan it yourself with out thinning you'll get it cured most likely but soft.No.You'll have to work that hide softening to get it soft somewhat.That's fun too.It'll weigh a bit I tell ya.A rug would be the best it can do for usefullness.
Good score though.