WISKI -
I know how hot that Texas sun can get - I lived in San Antonio for a year and in Fort Worth for many years. OK - many, many, many, etc...
I would think the tape would be the first thing to break down, but electronics can be vulnerable also (from what I've read). No first-hand experience because I've always been careful with my equipment and tape.
When we load the car for a summer wedding shoot, the cameras and tape are the last thing to be loaded - right before we get into the car and start the a/c.
I've read about putting tape and electronic gear into an ice chest with one of those blue ice things. As a side benefit, they claim that your gear is less likely to be stolen than if in a camera bag, but here in the South you'd need a sticker on the ice chest saying "This chest does NOT contain beer", to decrease the chances of theft. X-D