Have you tested your lenses to see how they handle lens flare/ghosting from lights when it’s dark? I’ve never had a problem with mine, but I’ve always checked a new lens to make sure.

In low light I use manual mode with auto-ISO, I put the lens wide open, and I vary shutter speed to keep the ISO reasonable while keeping shutter fast enough to avoid blur. I might stop the lens down a little for more depth of field, if lighting allows. The parade might be lit up enough where you can get away with auto exposure. I would scout out the location and see what the lighting is like at night.

Changing lenses out in the open at night with people walking around is one of my least favorite things to do as a photographer. I’ve seen parade photographers in my area with two bodies, they seem to favor 70-200 and 24-70mm. I also shoot with two bodies but I don’t have those lenses yet.

When I’ve shot parades I find a spot with a couple of good vantage points near each other, like a corner where the parade rout makes a turn (so I can take pictures from “in front of the parade” without actually being in the way) that might be near a picturesque or recognizable back drop like a fountain, park, fire station, town hall, library etc. I scouted out what I thought would be a good spot, and the professionals came to the same spot.

It seems like the photographers and town employees are friendly with each other and they build some good will by taking pictures of all the fire fighters and EMT responders if fire trucks and ambulance are part of the parade.