Years ago when I was riding enduros here in New England, I used a helmet visor that had rearview mirrors built into the helmet visor. Once you got the hang of it, they worked pretty well. Anybody out there happen to have one they're willing to part with (other than some dude on Ebay who claims his was owned by Steve McQueen and he wants over $300 !)

PM me if you have one. Thanks, Will