This is what i came up with to even the balance. Not shown in pics are two new 2mm shorter outer battery stoppers in 2.5mm cf. Identical otherwise to the originals but shorter. Made the holes 2,7mm so I could set the screws directly in the cf without a nut. It works and it is rock solid.
This moves the lipo 2mm closer to centre.
Pic1. A 1mm thick cf plate witch is 5mm wider than the chassis so electronics can be mounter further out. Only one hole shown in this pic but I made two so both holes in the chassis secures it firmly. Also used the hole in the servo mount so everything is one piece.
With electronics mounted
Shows the 0.5 mm space between chassis and tray. The tray doubles as a battery stopper inwards also.
Tray mounted in the car.
The idea is to even the balance and now my ride weighs race ready 1349g with a mazda speed 6 Lw body and the balance is perfect. Got space behind the esc for a motor fan that will make race weight legal.
Another advantage with this is the ease of maintenance in case of a quick chassis swap or some soldering work on the esc. It does not affect chassis flex either.