Fog Lamps on a 65

I got a set of repro fog lamps, bulbs, and bars. I am trying to figure out how they go. I think I have them together correctly, but is there really just one bolt and nut that hold the fixture to the bars? Seems like that would loosen up awfully quickly and be flopping around in no time.

Any suggestions? Thinking about putting another screw or small bolt through the bar and fixture just to have more than one anchor point.

I still have the original non-gt grill but got the gt brackets. The did not fit perfectly so I had to alter them to fit. But got them on. They seem to look pretty good. Still have to rivet or screw the gt brackets to the top and bottom of my grill.