Absolutely echo this.
I understand your concerns. Truly. With my horse’s injury, it’s very possible another horse would not have survived it much less returned to work, because he was just such a good patient, and so many horses are not! But sometimes just getting out of the stall a little bit as allowed—your small dry lot run out and the concrete aisle—can help the mental state while keeping them under control and striking the best balance between the horse’s sanity and allowing the injury to heal. But strict stall rest and being mindful of surfaces is really the best in the beginning if you want the horse to recover from a fracture. Doing more than recommended for her mental health might leave you with a horse that’s alive next year but permanently lame.
I echo looking into a rehab barn. They really can help with keeping them quieter. My friend’s horse was not a great patient and was on a lot of chemical support when resting for her P3 fracture even though she had the company of my horse next door.