Rethink exemption status of traveling sales rep

Q. We employ sales and service reps who travel and service stores around the country. They work from their home offices, use their own cars and communicate with us via phone. We classify them as exempt. Is this correct? (Most reps are required to spend at least eight hours at each location. Some drive three hours or longer to get to each store. We encourage overnight stays under these circumstances.) —L.C., Oklahoma