Given your condition, I strongly support your determination to stay in the UK, and I applaud your fiance's willingness to do what it takes to make her credentials viable over here.
Getting that work visa is really difficult. But spouse visas are just tickbox visas. If you demonstrate that you meet the requirements, you get the visa.
If she has at least £62,500 in equity in her home, she can sell her house and use that equity to satisfy the savings route for a spouse visa. I understand she'll need those funds to cover her moving expenses, but not 'til she's moving.
What if you flew over and you got married. She sells her home and puts the proceeds into her bank acvount and applies for the visa. (She'll need to be able to stay temporarily with friends/relatives, or rent a place, and she'll need to pay for storage of her household goods, but she'll still be in WA working, so her salary should cover these expenses without touching her savings). After the visa is approved, she flies over for a visit and to collect her BRP. At the time of this first spouse visa entry to the UK, she will still have the savings, so the circumstances of her application will still be correct. She collects her BRP, flies back to the US and actually arranges the big move, spending the savings as needed.
For the next visa application, 2.5 years after the first one, her income from work will count. So as long as she's able to find a job that, combined with your income, pays at least £18.6k for the two of you, you're all set. (For her first spouse visa now, her income doesn't count but her savings do. For the further leave to remain (FLR(M)) visa, and then the Indefinite Leave to Remain (ILR) visa she will apply for from within the UK, her income will count.)