Actually, this is the way my mind originally turned. Thinking I could put a emitter/detector pair on one side, and a white surface on the other as a reflector. Got a laser LED element floating around here somewhere.....
Have to admit, I have a Rube Goldberg tinge that wants something not completely simple.
The airplane HAS a strobe, but it hasn't been hooked up for about 10 years. Ran out of panel space/enthusiasm for switches/fuses when I re-did the electrical system. Ditto the nav lights. Dates to the building of the aircraft ~40 years ago. Hardware-store wire used; not too fired up sending strobe pulses ~10 feet through it.
The strobe itself is mounted to a big shaped balsa block on the vertical stabilizer...totally ruins the lines of the tail. I've temporarily removed it, in the past, to mount a video camera instead.
I tend to cover it in shame, on the ground....
Ron "Good place to keep the formal flying helmet" Wanttaja