Thanks again brutus.!!
1) I will go with one 4S 2500mAh NiMH to feed the CDI separately via the kill switch.
2) Rx, servos, gyro...etc will be fed by two 5S 2500mAh NiMH packs connected via a diode bridge as shown in attachments.
Further I will keep 1) and 2) above as far apart as is practically possible to minimize Rf interference.! As mounted right now the CDI module and the Rx antennas are 14 inches apart.