You certainly will be putting those drivers through a torture test with environmental extremes, but like you said you're not too worried about them if they fail etc.. The other day it was a mild 22c out, and my little Yaris was sitting in the sun.. I opened the door to go somewhere and couldn't believe how hot it was inside, had to leave the doors open for a bit to air it out before I could go or I'd be in an instant sweat. Anyhow hope it all works out for you, sounds like you're getting some good info here, hope they hold up