well, im happy to report that after lots of tests, the apoxie sculpt seems like a good canidate for this project! it sculpts like clay, and after it cures is like fiberglass as far as hardness goes.
here is the rough shape of the lower rudder
here is where the rudder sits now. its been shaped, and i filled the low spots with more apoxie sculpt. waiting for that to cure now.
so thats where i sit now! the upper rudder is curing as we speak! updates tomorrow i hope!