"Trains" Themed Parade Float

If there's a way to do it, fitting the front of the vehicle with something resembling the old-fashioned cow-catchers would be cool. Perhaps posterboard or cardboard might work. Bet you could create smokestacks out of several large oatmeal boxes stacked and fastened together with strong tape like duct or packing tape (depending how much space you have.)

Trains....one of my favourite subjects. How about lanterns? They use to use them to wave down a train if they wanted it to stop. Engineer hats on the cubs heads. Red triangle scarves around their necks, blue jean overalls. They could be blowing on a wooden train whistle. They actually sound like an old train. Black and red could be the main colours on the float. An old station sign of your city on the side of the float. It could be made from large sheets of plastic foam, burnt in wood, made from brown paper and stained to look old with a spray of plastic to keep it through a wet day, etc. Google old fashioned train stations to see how the signs looked.