Your best bet is to use bread warmers. Here is what I recommend… to have a hot potato that is dry and fluffy, as well as being able to store the potato in foil for an extended serving time, bake the potatoes at 400 degrees F in a convection oven without any foil. Once the internal temp is 185°F or more (210°F is ideal) pull the potatoes from the oven, and with one hand using a mitt, place each hot potato in foil and wrap. Ideally store in a heated bread warmer drawer. Another option are the portable warming cabinets (sometimes used to slow cook meats or in catering and banquet business). Placing under heat lamps is second best but the outer edges away from the light won't keep as warm, placing in a steam table insert is third best as this introduces moisture. The only way you can achieve a superior tasting potato for most of your customers is of course to batch cook like Wendy's used to specify.

Here are a couple of Dr. Potato articles:

• How To Prepare Baked / Twice-Baked Potatoes
• Why not to use foil: How Can I Keep Potatoes Warm Without Drying Them Out?