I was able to paint the mirror bases today. I waited until the paint was dry to the touch, and attached the sport bike mirrors. They already look much better than the other ones. Here are a couple photos.
They're not perfect, but should look fine from 5 feet away. And that's good enough. It just needs to be presentable. This isn't a show car.
I'm tempted to install them right now, but the paint needs to cure some more. Right now it's at the point where it can be handled, but you have to be careful. So I'm going to let it dry overnight.