I have pondered the idea of having a couple pound weight on some type of pulley in the tail cone that could be moved forward or aft while in flight.
++++++++++++++++++ There is probably a great deal to learn from this, but rather consider using water pumped around between two tanks. Five liters would be 11 lbs (10L would be 22 lbs) that could be moved from the header tank position (or under the seats) to somewhere far aft - maybe mounted to the tail wheel hard points. A crude dump valve on the rear tank may be a good idea - just in case. If the fwd facing wall of the aft tank is designed accordingly, the tank would contain say 4G's of flight load, but rupture (in the unlikely event of a prang) and allow any water content to escape, leaving the tank to stay put and the water alone coming for you. Tell the FAA inspector that you have an automatic fire sprinkler system installed. Some airliners use fuel in this manner, but probably not a good idea in this case Steve Jacobs
