This isn’t technically a mail- order bride book because it’s a miscommunication, but Healing Hearts by Sarah M Eden is a frontier romance that starts out with a young woman going to Wyoming territory where she thinks she’s going to be a nurse. I’m not giving anything away because that all happens in the first couple pages. Very clean. It’s actually book 2 of a series but I hadn’t read the first one and wasn’t lost.
I’ll post more if I can recall them!