I just lowered my body down as low as it can go.....but some sort of support in the center is a good idea. maybe use a foam block of some sort with strong doublesided tape to the underside of the body? I also gorilla tape the the weak parts of underside of all my bodies for extra strength.
I put this metal rod through holes I drilled in the front body posts. I had the posts smash through my proline F-650 body after many upside down landings. this will prevent them from going through again
thanks for the pictures of the battery and how it fits.