I use the IP 3800 Lipo's in my BD and use the stick pack retainer the same as capellone24 has in his picture. I have placed the extra weight required on top of the battery, which meant that I had to raise the battery strap by two mm. I placed this spacer in the middle of the battery posts. I do not use the rear top deck brace.
I have not tried a trackpower battery, as I believe the only way to fit this is by taping the battery in, with the battery over hanging the chassis. I could be wrong, perhaps someone can show a picture of this fitted to there BD.
Thanks for all the good info on your racing and BD setups.