I recommend using the CIPA Rearview Boat Mirror - Convex Glass - Windshield Mount # CM11119 because it has a smaller mirror face than a lot of the other available and comparable mirrors since it is 8" long by 2-1/2" wide. This mirror will mount on round or square tube windshield frames 7/8" and smaller.
I've linked our review video of this mirror as well as a picture that shows this mirror in use by one of our happy customers. I've also linked our entire selection of boat mirrors in the... view full answer...