I tried the vive tracker as a light gun route myself and used the precompiled vive controller as a mouse pointer as well. I ended up getting this gun (Hyperkin Hyper Blaster) to attach the vive tracker to:
How did you get the calibration to work? For me it's always all over the place, and there's no good way to adjust it.
I saw the hyperkin guns, but importing one would've been overly expensive, and they mounted the tracker on the top so you can't use the iron sights without heavy modification anyway. I found it easier to just mount to a guncon, you can put a tracker in the hole for the cable with minor modification to fit a tripod mount, and then you can use the iron sights and wrap a couple of wires around the pogo pins for a trigger and A/B. I've tried some alternatives, but the required minimum distance is just too much for my setup, even with fish eye lenses. I could use a smaller screen or move further away, but I want to play on a big screen, and that requires both a large screen, and a low minimum distance. Right now I'm playing with my gun barrel about 9 inches from the display, I think even camera based laser detection would have problems here due to occlusion.
As a basic example, at this distance on a 4:3 game I have a horizontal view angle of 50 degrees. If we assume you can get about 1x diagonal resolution away from a screen with a fish eye, and you're playing with an outstretched arm instead of shooting from the hip, you would need to be around 60 inches away (40 inches due to screen, 20 due to distance from barrel to eye), giving you a view angle of 26 degrees, or almost half as small a picture. With a much larger screen, barrel to eye distance gets smaller proportionally, but even with a 200" display (which would give you a 163" 4:3 screen), you'd still only manage a 33 degree horizontal view angle.
Obviously, there's an argument to be made about what view angle is good enough. Time Crisis 3 deluxe had 50" 4:3 screens with the player about 60" away from the screens, which corresponds to a horizontal view angle of 37 degrees. Standard cabs had smaller screens with lower view angles and are still totally playable, but I'm looking for arcade level without having to rent a warehouse to fit a 300" screen in so I can stand 27 feet away.