The wound is extensive. It’s a very invasive procedure and looks quite gnarly. I would not be putting this horse out, too risky if she gets away from someone and rips the sutures, or gets it infected. Also, no guarantee she’d stay calm in a little rehab paddock - a lot of horses don’t. Especially the ones that are herdbound or lacking confidence (like this mare).
I also highly suggest a rehab barn until the wound is healed and she is able to go outside. They’re going to be set up and prepared for this type of thing. Most boarding barns are not able to accommodate it easily even with an upcharge and moving horses around. A rehab barn will be prepared with buddies so she isn’t in the barn alone, and has trained, knowledgeable staff.
On that note, OP, I’m sorry but I don’t think you’re equipped or prepared to handle a stall-rest version of this horse. Not without heavy sedation (can you administer IM injections if she won’t eat a feed through sedation?), and maybe not even then. I feel for you and I think you’re picking up skills fast, but I would highly caution you against DIYing the stall rest and hand walking part if you do go with surgery.
In my area the vet run rehab barn is about $3000/mo base board, but I found a private place for much less (no vet on site and less sterile of a place - care is just as good though).