BoneDoc,
Here is an easy way to move the C.G. way back[>:] by using only scrap foam and velcro-------

1. Take a few pieces of scrap foam approx. 1"x 2 1/2"
2.Take some epoxy and layer the pieces of foam on both sides of the front and back compartments untill they come up flush with each other. (Mine took two layers)
3.Once you have a level platform take a piece of velcro and lay it across the gap, and voila- you have a nice level area to slide your batt. in the extreme aft C.G. ranges.