I managed to avoid being passed in that video ^_^ Was very nice meeting you and seeing your car in action. I do think the 1 series is at fault for your high temps. I'm going slower on street tires, but didn't ever get close to needing a cool down lap like in the video.
Here's one of my (low quality) videos from the same day; chasing down one of those high powered Mustangs.
10 Minutes on Shenandoah Circuit - YouTube