Make your timetable consistent with occasional stops along a side road where your leashed dog can find relief. Many veterinarians do not think the Rest Stations along the Interstates are a particularly sanitary area for your dog. Not that you have to be fussy but why not select an area that avoids conditions where dozens of dogs have already baptized the environment? And be sure to have some ?Pooper Pick-Ups? with you so that in the event of an unexpected deposit in a public area, you can perform the courteous cleanup immediately.