For the SE mine was way tail heavy as well. To get the CG right, I have my batt on the upper tray 2150 15C pack 142 grams. I also put my GY401 on the lower tray near the motor, yeah I know should be at least 10cm away to prevent glitches, have not seen a problem yet, other than drift. I mounted my RX on the bottom of the battery plate. ESC is mounted in the rear inside the body, right under the main gear, gets lots of airflow to keep cool, and I extended the battery leads to reach up front to the battery. I now have almost perfect balance, if I can move the RX about 2-3 CM further fwd will be dead on. I have some left over black ABS I might make an extended battery tray out of to be able ot move the RX fwd some.

I have not done much inverted flight, so don't know if my trims will be ok there. At this point with the sub trims set to get everything centered, I think I have one click of ele trim to keep it level in a hover.

Maybe RaserX's suggestion for the GYRO will work, I have the 401 so can't help there.

Pete