how about the cen rear mounted battery box, for the rx, and another smaller box for just the batts? i know u want to keep the original box, but its hard to make it work...

or - rx in rear box, and zip tie the batts to the throttle servo mounts?

my batts are ballooned and zip tied like that, and my rx and failsafe are on top of the steering servo all in one balloon and zip tied together. gotta love zip ties...

good luck mate, it doesnt leave much room does it?!?!

whats the plan with the exhaust? out over the back or a long headered side mount?