Yes, for FAFSA purposes, she could fill out the parent’s section as separated. Even if they file a joint tax return, she’d only use her income and assets, and it gets a little tricky but it can be done. File early! as you’ll be asked for additional documentation. With just her income, you might qualify for Pell grants and other federal aid.
You should get lots of merit aid if you choose wisely, but don’t dismiss UT-K or other schools where you can use Hope or other Tenn programs. My daughter stayed in Florida in part because of the resident grants and Bright Futures.
If you really want to get out of the south, go west and north. You’d get a lot of money at Wyoming, Montana, South Dakota. Look into one of the Kansas schools. However, I don’t think any of them will be better for you than UT-k.