Do you have any pictures of your fabricated mount and what did you use for it? Can you utilize your mount to attach V1 on the top of the mirror?
The set screw on the mirror attachment is typically below the height of mirror. It would require double articulation to get it above the mirror.
What I use is an articulated mirror, typically found in the tools section of a good computer/electronics supply store. Cut to desired length both sides of the articulation joint and then use your tap/die set to get it all threaded up. Mounting to the detector carrier bracket depends on the type of detector, so you might have to do a little engineering. With the ****** Passport, take the cups off, bend the bracket up to desired angle, shape (cut off the "ears"), drill a hole in the center, and attach with a nut and lock washer (use a nut and regular washer on the mounting arm side for stability). You can paint your backet any color you like -- I do mine in black.
So if you're a DIY person and enjoy doing a little fabrication, this little project makes for a pretty slick detector mount. If you don't want to do the articulation, you can come straight down from the set screw to the ****** Passport bracket bent to the desired angle (this is a little sturdier).