Re:keeping potatoes warm
Personal preference, I have always held breakfast potatoes on the grill. It keeps them HOT and somewhat crisp, depending on how long they are holding for.
How many breakfast covers are you doing?
When I did movie catering, I could get 300 people fed in an hr or so, all cooked to order on a 5ft grill, potatoes on the cool side of the grill. Used the grill for breakfast sands, burritos, french toast, pancakes, etc. Pans for omelettes, OE & scrambles.
Sometimes it was not pretty, but it's what we had to do.