I need to keep at least 500 to 1000 large Idaho baked potatoes hot for about 8 hours and still be able to serve them up. I know from past experience that I was able to keep them relatively fresh by using an ice chest. But that was only for 150 large bakers. All I have for heat are two large BBQ's. Please let me know if this is possible.

I really don’t know how you will be able to do this without compromising the appearance of the potatoes (the skin will wrinkle after 2 hours, never seen them after a full meal period of 3 hours) or the food safety issues (hot food hot, cold food cold and the danger zone is in between). The only thing coming close in advance preparation of the potatoes would be warming or holding cabinets, as used by catering companies, hotels or hospitals for delivery of food from commissaries. These still need to be plugged in. They can keep product warm or even slow cook things. Here is a link with some examples.

Unfortunately, I think you may be out of luck…