I just bought a bunch of Ace Hobby 4.8V 700Mah NiCd receiver packs with Futaba connectors on them for $9.12 each from http://www.infinitehobbies.com. Why waste one of your LiPo packs for receiver duty when you can get such high quality receiver packs for so cheap?

In glow planes, having a receiver battery with a little bit of weight to it is actually advantageous. You can adjust the CG simply by moving the receiver battery around the radio compartment insteading of adding lead to the nose or tail. The extra weight of the NiCd battery is negligible on a 4.5 to 5.5lb airplane.

The part number for the Ace Hobby batteries are:

ACE2906J - Flat pack with Futaba/Tower Hobbies connector
ACE2906A - Flat pack with Ace/Airtronics connector
ACE2906S - Flat pack with JR connector
ACE2907J - Square pack with Futaba/Tower Hobbies connector
ACE2907A - Square pack with Ace/Airtronics connector
ACE2907S - Square pack with JR connector
ACE2907SI - Square pack with ??? connector (Only $6.08, maybe no connector)

At prices like these, there is no reason to use a LiPo battery for receiver power.