I don’t think ATP is your best option.
With decent weather you can do 0-CPL at any decent school.
Which means you could have your CFI in 6 months.
My knowledge may not be up to date but I thought the GI Bill paid for most (70%?) of your training after the Private.
So you wouldn’t need a $70K loan.
AFAIK GI Bill requires Part 141 training and many schools hold that certification.