Running a rear wing puts a lot of strain on the rear body mount. Many have made all sorts of braces to strengthen that body mount. Here's my take on it. Very light weight and much stronger than it looks.
The parts
A small piece of 3 mm thick carbon fiber to fit over the rear shock tower, some nuts and screws, a brass insert for the rear body mount and a rod with ball ends glued at each end. The rod is a carbon fiber rod, I drilled the ball ends so that they would fit snug on the rod with CA glue.
If anyone wonders if the ball ends will stay on the rod, stop wondering. On my nitro Revo, I replaced the sway bar turnbuckles with the same kind of CF rod and it hasn't failed after using them since 2006.