I'm using a LiFePO4 battery in my Insight, which has been converted to a conventional gasoline car. Mine lives in the cabin also, and Vermont's summer weather is far milder than Tennessee's. I have supercapacitors to handle starting current and subsequent charging during winter and though I haven't done a load test, so far so good, seems I haven't killed it.
https://www.batteryspace.com/li-ion-...lead-acid.aspx
Different chemistries have different characteristics. BatteryUniversity says that thermal runaway on LiFePO4 is ~270C (~520F), though I'm inclined to believe that you wouldn't want to be anywhere near that for longevity.
https://batteryuniversity.com/learn/...of_lithium_ion
I believe Lithium Titanate would be the safest choice if you could find some cells for a reasonable price - NASA uses them in their spacecraft, and they handle the temperature swings found in space.