I did that last Friday. It was a night parade, no sky light, with inadequate street lighting, on a narrow two lane old-time urban street. 50 mm was definitely too long (on full frame) for many of the shots but I managed to place myself at a turn in the road so it wasn’t awful. I exposed for the highlights, which consisted of a multitude of Christmas lights on each float, and a lot of the shadows were indeed rather dark. The lens was a f/1.8, and most of my shots were f/2.2 at rather elevated ISO. My keeper rate was well below what I’m accustomed to. Definitely I’d use a wider lens were I to do this again, like maybe my 28 mm f/2.8, and I’d shoot it wide open.