I've used some trailer clearance lights that mount using a single stud. They're usually rectangular in shape however, with one hole for the mounting stud and another for the wiring.

Here's one that might work for you.


Kevin
1951 Chevy 3100 work truck
Follow this saga in Project Journal
Photos
1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.