Bruce, your layout looks great!
If you don't mind though, I'll set the record straight on Homasote vs. Masonite- not the same at all. Homasote is a sound deadening material like compressed cardboard usually about 1/2" thick. Model railroaders have used it for track underlayment for years. Makes a horrible mess when sawn!
Masonite is a thin 1/8" or 1/4" hardboard manufactured panel that model railroaders use for back drops and fascias. I assume you used masonite for your backdrops, since homasote would not bend without kerfing it.
