There isn't a for the flavor of chipotles, so leave them out if you can't find them. You can, though, duplicate their hot kick by adding 1/4 teaspoon ground red pepper (cayenne) to the mayonnaise mixture.
Round red or round white potatoes usually take longer to cook than sweet potatoes, so note in our directions that you may have to cook those a little longer.
Chipotles are smoked, dried jalapeños with a wonderful rich, smoky flavor. They are sold dried whole, ground and in cans with spicy adobo sauce.