It was much simpler than first thought. I guess once you take a little time to map out what you're going to do, it just comes to you.

I opened up the access holes just up to the formers( There were only formers on the bottom half of the tail, On the top half only sheeting.)

Cut balsa sticks to length... then had to sand the edges a little to get just enough of a snug fit. When installing the balsa, I used dental floss to help me maneuver the wood into place as I wanted. Will tack in place with CA, cut floss, and glue all around. Will then replace sheeting and cover it back up.

Thanks guys!