You could simply fill it a bit past her legs (enough to cover her butt!). That way she can't launch herself out. Then just let her waddle/swim in that.
Does she not like water at all? Just curious! I don't think I've ever met a duck that hated tub time 😱.
Wow, that's definitely a first for me. If it were like any other wound I'd say to clean it up and apply Neosporin, but I think it's going to keep having issues due to the area it's in.
@Isaac 0 may have seen this before. Or @Eggcessive @sourland @azygous. Any of you guys?