I encourage you to look in to degree granting institutions that offer flight training for hours. There are a few options (if you're willing to relocate) that offer A.S. and B.S. degrees that include flight. Applying for additional student loans, while scary, would still be far less than ATP. You may also be looking at a reduced time frame if you can transfer any of your credits from your other degrees. This would allow you to use R-ATP minimums as well.
It's more or less what I'm doing.