After test assembling the plane with everything in about the right place. I found that the CG was a little in front of where it is meant to be. Without adding weight to the back there would be no way to balance the model and make easy adjustments. So I decided mount the battery over the wing, so made a battery tray.
I am currently replacing spar that goes about the new battery tray to reinforce the fuselage.
The retract value was integrated into the battery tray.