Thermal storage needs to be quite large though, at least with the stone/brick like mass they used back then. And you need to isolate it, otherwise you have no control over the release of that stored heat. I wonder if new materials, maybe something that undergoes phase change in that temperature range, could be a lot more space efficient.

I don’t know how remote your mountains are, here there would likely be a charge point less than 50km away but I don’t know where you drive. I give you that.

Your second point though, you might want to reconsider your driving habits. Random google result for breaks when driving: “If driving long distances, you should stop for at least 15 minutes every two hours. Stop often to rest for at least 45 minutes every 4.5 hours of driving to avoid getting tired and stay alert. Plan to stop for a break every 100 miles on your long road trip so that you can relax. Try to only drive for 9 hours a day.”

How so, I’m curious? Do you drive into no mans land hundreds of miles away from civilization or are you a robot that never needs to take a break?

At least it doesn’t look like chocolate stuff, always great to get those turning white because they baked in mid summer heat.