What are my options for extending my stay in Thailand on a Non-O visa after 90 days?

Unless you're married to a thai or have half thai children there are none.

That visa has ONE option for an extension and that's a year extension by banking 800K baht in a thai bank account in your name only for 2 months before you apply

You could come in get the 90 day stamp, then either:

exit / re-enter on a free 30 day entry stamp (which you could extend one time for 30 days at the immigration office for 1900baht)

OR

exit and go to a thai consulate in a nearby country and buy a single entry tourist visa which would stamp you in for 60 days.

Those are your choices..