The problem i can see in your idea Patrick is the linlage. The servo use for the brake is put near the motor, and you have to route a linkage for the front brake and another one thrue the rear diff
Don't know how to place it.
But you seam to have somes realy good idea, i'am sure you'll find something
You'll have to find a fairly long linkage to go to the rear of the car I guess, but I'm sure it would be possibly to do. I don't really know exactly how you could set it up because I can't see where everything will sit (mainly the brake servo and esc), plus I haven't had much experience with manual brakes, so I don't know all the tricks for getting them to work well.
One thing that may cause a problem is how much room you have in between the rear diff input (where the brake will be) and the rear chassis brace. I don't think mine will have enough room for the brakes to fit without modifying the chassis brace, but the mugen looks to have a bit more room.
Could you get Mike to make you a dogbone and cup for the rear end? Get flat spots put on the cup, so the brake pads can be put on it like usual and put the cup on the rear diff pinion . Then take your plastic rear center diff mount that got replaced by the rcm motor mount and bolt that in front of the rear diff to hold the brake cam and linkages. Basically shift the rear brakes to the rear diff. Don't know hard it will be to do, I guess it will depend on your layout, but it could be worth looking at if the spacer thing doesn't end up how you'd like.
You could probably keep your rear cvd, but just flip it around and use one of Mike's 1/8th diff output shafts on the center diff.
The hyper 9 has something like this, and I plan to do what you say on my jammin crt, as the kb45 will not fit with the rear brakes. The linkage can be straight, just has to be high enogh to clear the motor. Have a look at the hyper9 pics as they did it with a single linkage and it looks super easy to adjust.