trikkonceptz -
(good idea)
I got this bicycle handlebar mirror from REI :
Blackburn Multi Mirror
And mounted it like so :
But, I have noticed that one of the exterior bolts on the mirror is rusting badly. It also "wiggles" at freeway speeds. Not much, but it could be annoying. If I were to do it again, I think I would go for a snowmobile side-view mirror (snow implies no rust to me) :
Arctic Cat Snowmobile Mirrors
Rugged - Durable - Holds adjustment. - Lens - Flat 3.5 x 6.25 - Solid Black
ARCTIC CAT WING MIRROR - 2.5" x 4" convex acrylic safety lens (I think this would be my favorite candidate)
...
Also, as others have said, I think you could "adapt" auxiliary safety mirrors :
Convex Safety Mirrors
This one looks very promising as a flush "by itself" mirror :
Auxilary Wide-Angle Side-View Mirror (Medium)
CarloSW2