My next task to do when it starts to cool off is to have both fans work off the thermostat and have a simple 1 way flap above it so when one is on it will not draw from the other one.

I'll most likely set them at 80F and 100F or something like that.

https://quietcoolsystems.com/ makes an extremely efficient variable fan which would be totally awesome.

https://www.amazon.com/Quietcool-Attic-Gable-Ventilation-Exhaust/dp/B073ZNGR6S