Besides moving the battery can you move the tail servos to the back? That's a major project after the covering is on, I know.

If it were me, I would want the weight as far aft as possible, but not want to cut holes in the bottom for fear of weakening the tailwheel mount area. One option is to set the plane nose up, make a small holeon the bottom of the fuse toward the read, and drop in lead shot (fishing sinkers) so they settle as far aft as possible. Then pour in some epoxy to hold them in place. I haven't done this, there may be some pitfalls I haven't thought of. Andy