Too bad you didn't post here first! LOL I make pageant sashes all the time and they are about 3-4 inches across. I use sticky stabilizer and then a tearaway on top of the sticky where the embroidery will be. Works great. Your way will work well, too.
On another note, I need to try doing them with my Magna Hoop. Not suppose to have to hoop stabilizer except what you need to support the embroidery and you can just pin that on. The magnets hold the sash in place.
Don't you just hate it when the "experts" make a simple procedure complicated. :)