I have a 12' diameter silo that is getting a 60"x60" e-panel sign on it. I need to fasten the sign using some sort of strapping system since penetrating the silo is not an option. The strapping needs to be designed so that when the strap is tightened it will suck the sign down to follow the radius of the silo. I was thinking 4 20' lengths of 1/4" all thread with some sort of a fastener. Any ideas would be appreciated.