I wanted a way to add another rack at a right angle without restricting the access to the corner. I came up with this piece that allows beams to be supported off the accessory beams. 

This part works on the right hand side mirror for left hand take off. 

The only issue I have is that the back of the rack is a little unsupported so there is a bit of sagging. I have not noticed it except for when pretty heavy weights are added to the rack.

Uses 3 screws to attach to the accessory beams.