I just drove to Michigan and back, saw maybe 5 vehicles, including a semi covered in lights.

One just had a single dollar store strand around the hood, one had followed all the panel lines on the car, and the others were just wrapped a couple times over the top and underside.

None were flashing or twinkling, just steady lights.

As long as they don't flash or move while driving, honestly I don't think a couple strands would be that distracting except maybe a double-take

I can see how this many lights would be distracting for some. I would definitely look more than twice, if I had space around me.

Still though I think I'd just ask them to leave most of the lights off while actually on the move at most.