As you can see in the pcture, just to the left of the mockup, the 2X2. The crown moulding will be nailed in every 16 inches. The moulding is a foam form, very light weight. I think it will be ok without a gusset, what do you think??
I have a sheet of 1/4 inch masonite, I could lay that down across the 2X2, giving my a brace/gusset that could be glued in place. That would give me a place to install rope/black lighting too.