Outdoor dance floor after the sun goes down

I had an issue come up for the first time while shooting a wedding last night. The venue was outdoors, the ceremony started late and by the time dinner was done the sun had already all but set. Next up was speeches, not a huge issue as I had lights and there was still just enough daylight to get focus. But then it was time for dancing. The DJ had some lights on but not much, I had my lights set up around the dance floor but my problem was grabbing focus.

What would you use to help with focusing, would a video light be the best bet or mounting a small flash light on the camera maybe be better?

What do you use to trigger your lights? A lot of options for focus assist beams, I use YN622's which have them included. Only advantage to a video light for focus is that you can still use AI Servo focus (Canon).

I am using the YN603's which is a very basic trigger. I will look into the 622's

Flash on the hotshoe with an AF assist beam, 1/128th power if you don't want direct flash, or even point the flash up in the air. Radio trigger obviously for off camera. Use a reasonably fast lens so focus is quick, F2.8, but you may want to shoot closer to F5.6 to account for moving people and slower focus.