The re-finance (getting her name off the title) and rental could work. The reduced rent option is likely the best scenario, long-term (i.e. after your maintenance payments stop).
I originally offered to do that for my NJ and her kids, but she's too ******* stubborn to see that's the best option for them. She'd rather be a thorn in my side than do what's best for her kids. I was going to rent the place to her for less than the cost of a 3BR apartment.

$1,355 to rent a 3BR 2.5 BA house with a fenced yard (she has multiple pets) vs. $1,500+ to rent a 3BR 2BA apartment that she's lucky if the landlord will accept even one of her pets.
Just consider yourself fortunate that your STBX at least is processing what she needs to be doing for the sake of the kids.