Well it's definately necessary in that perspective... I don't plans on useing mine that way. Primarily I want it for added privacy when on Boy Scout campouts(I'm an Asst Scoutmaster). The BSA has rules and reg about changing with boys around. Otherwise I'd stick to the stock tarp that came with my HH EXPED.
Don't knock the old sewing machines. Most are still great workers. The one I currently use is a singer manufactured in 1909. Yes, its 100 years old, treadle operated, and works just fine. (being able to steer fabric while doing the feet moving is a little like learning to play the drums, but you get used to it.)
Nice work. It made me dig my wife's "gear making machine" out of the closet. Now to think of a project ....