If anyone's interested, I followed up on requesting a cash upgrade clarifying that I'll take anything:
I did want to clarify that I would be very happy to pay a cash upgrade fee for any portion of my stay, even for a single night, to any of the sunset, St. Regis, or panoramic overwater villas.
And got this response:
Further to your request, please be advised our rates are entirely dynamic and while we are regretfully unable to provide a cash supplement option in advance, we have your request updated in your booking and rest assured, should there be any cash upgrade options that open up for December 2022, we will be happy to inform you promptly. And should there be availability on arrival, we will offer a special supplement for your kind consideration as well.
Sounds fairly unlikely I'll get anything by waiting since this stay intersects the holidays, so that's unfortunate. There's definitely currently cash availability during my whole stay for Panoramic + StR, plus ssOWV for a portion, though. Any reassuring words from those who tried the same thing or am I doomed to worry for the next 10 months?