Walls and Ceilings - Climbing wall addition.

I'm attaching an 8'x8' climbing wall to the exterior wall of an 8'x8' shed. The climbing wall has 16" stud spacing and will be attached to the shed frame (which has 24" stud spacing) along the studs at the ends and middle, as well as along the joists.

I want to add an overhanging section to the wall, which would start at 7' from the ground, extend 3' outward and 4' upward. This will be bolted to all the climbing wall studs.

I need help supporting the other end of the overhang. The top edge will be at ~11', which is 3' higher than the top of the shed. My plan is to sink 2 14' 4x4 posts, laterally brace them with 8' 2x4s, place 4x4 scraps between the braces at 16" intervals, and secure the ends of my overhanging section at the 16" intervals.

The overhang will only be supporting a 200lb person and a 4x8' sheet of 3/4" plywood.

Do I need to use 4x6" posts?

2x6" braces?

Is there a better way to secure the studs of my overhang to the braces? (To screw down through the tops, I'll have to attach them before completing the brace structure).

Any way to save some $?

Thanks.

I think your methods and materials will suffice. I would make sure they will withstand the weather. For instance, what will you do with the water that falls behind the wall? I am assuming this is outside. If not, my apologies.
Or you could do this:http://i76.photobucket.com/albums/j3/larrychandler/DSCF0556.jpg
Good luck with your project.