I cut a hole in the bottom sheeting just in front of the lower fin. Then I built a box in it and made a ply door. I would have liked it farther back but the ventral fin made that impractical. Even so, it saved several ounces.

With a 5 cell NiMH pack in the hatch and servos all the way back in the radio area, I only needed 2 1/2 ounces on the tail. I think initial estimate was around 7 ounces of weight on the tail so this saved a quarter pound of lead!

Dave