Doing it in sections will work fine. All your glue lines will be lost in the design of the overall profile. I did something similar to this years ago using three different crown moldings to make a mantel for our fire place.
That was a very easy fix. Stop lights have a heating element that is triggered during snowfall to melt the snow and ice. Uses a tiny fraction of the energy compared to the old stoplights. This isn't including the reduced downtime to burnouts.
Teenagers? bah I still take 45 min showers. It's frigging COLD here!!!!