@JohnB007 @boones totally agree. I bought the bag for outdoor/tent camping. Couldn't pass it up for $60! I'm planning to set Model Y temp to hold at 60F and use some lightweight bedding.
Also, I can relate to the comment about aches and pains and age. If I'm going to be sleeping in the back of a car, I really need the best mat possible. And after a few nights in the car it's pretty much paid for itself anyway. One night at the Yosemite Lodge is $300.
I'm really looking forward to this. Feeling like a kid again. I wish my wife was into it, but there's no way I'll get her out there with me.