For a sanding job that extensive make sure you are adequately protected from exposure to the partially cured epoxy dust. After working occasionally with West System epoxy for years, I spent the better part of a day sanding and fairing a repaired transom and keel area of an old dinghy. I was wearing a good mask, but the rest of my face and neck was exposed. Within 24 hours I was experiencing extreme itching and within 48 considerable welting and swelling in the face and neck area. I also got a bad rash around my waist where the dust must have settled inside my belt line. I apparently experienced a severe allergic reaction to the epoxy, not as uncommon as I would have thought. That was six weeks ago and I am still experiencing effects. It took an injection of prednisone to bring it under control. But once, sensitized, you are pretty much always going to be sensitized. An allergic reaction to epoxy has ended many boat builder's careers.