I've thought about building a set of electric bullets, too. My idea was to pull the motors from a 80's model GM and fit them into the bullet shell. Unfortunately, I've not even gone so far as mock-up. So all of the following is my unproven idea.
For mounting provisions, there are a lot of good epoxys out there that can be drilled and tapped. A simple damn can be made from masking tape to create the mounting ears and then, with a little patience, the mounts can be ground flat, drilled and tapped. It seems fairly easy but it all would depend on finding a motor that would fit into the bullets deep enough to allow the mirrors to mount at their stock depth.
I'd be interested in hearing about some other ideas and successes.