I grew up on a farm covered with poison ivy and I had many unpleasant episodes of severe incidents. My mother grew up with homeopathic remedies and she tried "rhus tox" on me. It gave me great relief. It wasn't a cure but it significantly reduced the severity I experienced.
Rhus toxicodendron...
I'm a woodturner and do a lot of sanding. I have found Klingspor's Woodworking Shop has the best abrasives available. Go to their website and look under Abrasives.
https://www.woodworkingshop.com/
You can buy disks or I have it more economical to buy Rolls and cut my own disks.
My tractor is a little smaller but similar to yours. Photo should give you an idea of what a grapple mounted on your tractor would look like---WR Long RGB2 54" wide on my L2800.