Problem solved.

I sealed the hinge gaps and she flies fine with a little LEFT trim in the ailerons, which is as it should be since the wing came out slightly tweaked after I joined it.

I also learned in reading around that my Futaba S3004s were too weak, as they only put out 44oz of torque at 4.8 volts and Aeroworks recommends a servo with 60oz for 3D flight. The S3004 puts out 57oz at 6 volts, so I just bought a 6 volt receiver battery. I don't really do 3D outside of the simulator anyway, so that should do the trick. Oh, and I stuck a 13x5 prop on there. The plane behaves itself perfectly at all speeds now.