I would use Underwoods and nothing else (except put the baking powder on that it calls for).
You DO NOT need to keep it clean. Putting water on it in any form after it has initially been cleaned up just promotes the over-growth of proud flesh.
It did not need stitches. It is what it is. The only thing that counts now is to get it healed up and keep flies and infection out. Underwoods keeps flies and infection out, keeps proud flesh out and will heal it up faster than anything else.
It is NEVER too late to give Penicillin, If you give her Penicillin, give 3 shots -- 1 a day for the next 3 days. It is fresh. It does not have puss in it. It is frothy and foamy from the serum that is oozing out. The Underwoods and baking powder will dry it up overnight and will start healing it the next day. Underwood Horse Medicine - Wynnewood Oklahoma
Here is the website that tells about Underwoods. Buddy Underwood lives a few miles from me and I have seen many horses that this stuff healed up that the Vets wanted to put down. Several are shown on his site under 'testimonials'. The Vets around here either sell it or recommend it. I am using it on one now and it has about healed up.
It is the only thing I know that keeps infection and flies out and promotes healing. It makes the hair grow back in the same color and I have healed up horses that you could barely find a scar on later.
If you use Underwoods you will not have to keep it wrapped at all. And above all, you do ot keep cleaning it or put water on it again. You do not need to.