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.