Yes.. large pressure washer, turbo nozzle, large angle grinder.. that way after you frame the skin, wash it get the hair dry.. then you can thin that baby.. rather than have that big skin kill ya. I have thinned a couple of elk on the Dakota and whew.. it's a work out.. it is a work out. .. did I mention that, it's a work out? well it is.. no bones about it. It just seems a lot easier to pick up an angle grinder and hold that then pick up the dang bison skin and thin it on a wheel.
Naw I got a guy a few miles away with a bison farm. Last time I saw him he was talking about culling them all and leaving for FL! They're all probably still around! Now's a great time of year though.. hmm.. should go check them out! I wouldn't hesitate to pull out the washer.. long as the machine's running the pump's not FREEZING! The angle grinders.. especially the large ones thin bison down nice.. just have to dull a new metal blades edge first so that it's dulled that way it won't cut the hide.. you know the large 7" angle grinder one uses during car repair or other things? I took the guard off of mine.. fleshes the crusty dried ones without cutting into the skin too. real nice..but it's very messy.. throws flesh and fat EVERYWHERE! that's if you DON"T have a power washer.. I like the power washer BETTER for fleshing.. quicker and easier to pull the trigger.. kinda gets water and meat and fat everywhere but it does a super job on the hair side too.. and those are usually a heckuva matted muddy mess. You absolutely NEED the turbo nozzle though.. don't use one without it. they don't work well without one and can cause plenty of damage.. well anyway just tossing out a few thoughts.. you want pics? I don't think I Have any angle grinder pics.. I got my garage wall all covered in meat and fat and hair from using one.. myself too! It works really well though, IMO! long as you don't hold the angle grinders in any one place for long while thinning after their dried.. There's a skill to it. You might want to have some slight idea on where they NEED thinning beforehand too.. Like the spine, flanks. near the tail. neck.. usually the shoulders do not require any.. go from thick to thin quick.. anyway hope this helps. I love working on bison.. they're awesome!

This was a young cow bison, a fall skin. Thin to begin with.. the holes in the upper part were from me thinking I was going to flesh it like a deerskin. NOT.. I used the 2400 psi washer on it.. and another buff.. it wasn't long before water was spraying everywhere out of that machine.. seals.. I was heart broke. It was in the shop before long!

This is my favorite 'tool' to use.. wash the bison skin with the washer and take a tool like this and boy you can see the yellow glues rolling down to the ground.. I stop washing when the water changes to clear! It's way cool. If I wash a deer skin with one and take my finger and rub it on the skins that I've squeegied off with the ulu shape tool the hide is squeaky clean.. how cool is that??