Soon to take a coast to coast trip, with most of the trip in the west, hanging around the grand canyon and utah trails. Off road is going to be a factor. Wee Strom is going to be the weapon of choice, but, the helmet.... Do street helmets preform ok on the dirt? Goggles are the biggest decision factor i suppose. Should I just get a dirt oriented helmet for the whole ride? I don't know how keen I am on taking one of each, BUT that may be my best option. ADV thoughts?