Thanks for all the kind words! This project would have not been nearly as good without the legwork done here already, I did a lot of research here on the boards to figure out exactly what I wanted and how I was going to pull it off.
I did learn a few things this time around that I would change about my original design next time around. Instead of framing up the screen then covering it in plywood as I did (which ended up getting covered by blackout cloth anyway), I would have simply framed up the screen then covered it with BOC, would have made this thing so much lighter and also would have significantly reduced the cost. Hindsight is a wonderful thing, isn't it?
I did use a high gloss/reflective paint behind the BOC, but this was only because I had originally intended on using just the plywood surface as my projection area.
The BOC has been through the weather several times already, it stays up all the time and it doesn't show any signs of wear or mildew yet. So far it's been out for about 6 months without problems. I think it's worth noting that my screen is fairly sheltered where it is and I sprayed a few cans of scotchgard on it to help protect against the elements. So far so good.
I literally just finished the stone work a few days before posting the pictures, my first attempt at any type of stone work and I have to say it couldn't have come out any better, you can put a level anywhere on the wall and it is perfect. I'm very pleased with how it came out, I'm going to be drilling the tops of the pillars this weekend so I can slide my tiki torches down into the pillars and some low level lighting is on the way for inside the stone wall to shine up on the screen when not in use. This will be setup on a dimmer so I can lower the lights as the show is starting and raise them when the show is over.

Their primary control will be a light sensor so they will automatically light the screen up at night without needing to be turned on. Should be pretty slick once I have it complete.
Sorry this post is so lengthy I've been waiting for the time I could post pictures for so long now lol...I also built a little brother for my BYT inside, I'll put up a few pictures of it when I get some time with the camera.