My solution is to run the BEC at 6.0 volts and have a 500 mAh 2s LiPo (about one ounce) backup battery regulated to 5.7 volts. As long as the BEC is working it provides all of the current. If it quits, the backup pack takes over and you save your airplane. Check the backup pack once in awhile and charge it if necessary.
Jim O
It sounds like your system works like the Scorpion guard, it's just DIY. May I ask what you use for a regulator?