Wow, MM... poor Jynxy...
My sister's QH sliced up his hock 2 years ago next September on a piece of steel plate in that exact spot on the other hind leg, but his looked a lot worse than Jynx's. Rio actually sliced 3 blood vessels - I was away at school at the time, but the blood-stain in the driveway alone was horrific. Our saint of a vet came out on the spot and stitched him up from the inside out. When we closed up the barn for the night there was a neat row of stitches under the bandage. By morning, Rio had popped the stitches and the entire wound was inflamed, almost to the point of turning inside-out. We spent the entire winter nursing that leg, and he took about a year to fully recover. Like I said, though, Rio's looked a lot worse than Jynx's.
The vet cleaned him up when she did the stitches, but after those popped we had to treat it just like an open wound. We just used generic triple-antibiotic ointment on a large sterile gauze pad on the wound, and held that in place with vetwrap. That dressing was changed twice daily for about 3 months, and once daily after that point.
The difficult part was getting the old dressing off, since the entire area was really tender. Our vet gave us some of the same anesthetic that she injected his leg with to stitch it, along with several syringes. We used that topically to numb the area, rinsing the wound with that while we prepped the new dressing - that did a lot for his pain reaction, and was really instrumental in our ability to change his dressings without getting kicked on a daily basis. The anesthetic is similar to novocaine: the vet suggested that we try it, but was skeptical that it would work topically, but it was THE STUFF to use. Vet actually gave us several vials that were just barely outdated that she couldn't use, but were safe for the job. We used TONS of Equate brand triple-antibiotic ointment; that also kept the dressing from sticking too badly.
After about 6 months, the swelling was almost gone, we'd start allowing him to stand without a bandage for some time, but we kept him bandaged if he was left alone in the stall to keep him from getting bedding and poo in the wound. This whole time he was on stall rest, some hand walking. Once the wound could hold itself together without dressings, he still had some swelling and tenderness for several months. A I said, it was about a year before he was back to full range of motion and total soundness in that leg. Today, he has some scarring around that hock, but moves great, no problems.
Be patient, it'll take some time, although I doubt as much as Rio needed. I don't know much about furazone or that controversy, but we had fine results with triple antibiotic ointment and sterile padding. Most of the problems that we had were keeping the bandage in place and keeping Rio comfortable through the dressing changes. He would fuss and fight through that, and get things bleeding and swelling again. The thing to watch with Jynx will be flies in the summer - the last thing you want is bugs in that wound.
Sorry for the novel, but hopefully you can benefit from my experience with a similar injury. Let me know if there are any more details I can give that might help you out with dealing with it. I may have some photos of Rio, taken through his healing process that can give you some form of a timeline, if you like.
Best of luck, and sending good healing vibes to Jynx!