I bought the Bell Pitman helmet (white) and another generic black helmet, both DOT approved. In Vermont the troopers don't care and a look of pain passes on their faces as they try to figure this out. New Hampshire doesn't require helmets at all. New York and Massachusetts do require them so if you start hopping state lines, which is easy, then it becomes an issue.
As a lark I left Vermont, crossed into New York, drove south to hit Massachusetts then came back through New Hampshire. I didn't even rack up 90 miles!
What's your mileage? Who cares. Is it practical? See #1. What happens when it rains? You get wet.