I am building a set that is rather tall for a show I am doing. There are several 12' flats that sit far upstage. They have a 3 foot clearance from the back wall. I need this clearance for a crossover. There is not enough room for jack-braces. I was thinking that I would cross-brace against the back wall for support, at about 10' out. I do not want to damage the wall too much, so those blue anchor screws are not an option. What I am really looking for is something that I can permanently mount into the wall, and then bolt into it when I need to. My mind immediately jumps to the "Improved Stage Screw", but I need something like that for concrete. I hope I was clear enough. If you think there is a better way to do it, I am open to suggestions. Thanks for your help!