Hi blackcat,
First option would be to make a device that supports the elevators during transport and when it is not being used. Full scale airplanes have gust locks that either block the controls or on older aircraft they locked the control surfaces to avoid damage from gusts. They would serve you the same purpose except that your problem comes from unbalanced control surfaces. Gust locks usually support the moving surfaces against solid parts of the aircraft.
If you are going through all the effort in making new elevators, consider balancing them weight wise. That will give you two really good advantages. First it will take off the stress that any kind of acceleration will put on your elevator along the vertical axis. In addition it will also decrease the load of the servos in flight, as CG of the elevator and the aerodynamic forces are closer together. Third - it will prevent flutter.
Technically you can design them in a way that with a little weight in the front area you can counteract the weight of the rear part. If your weight and balance does not allow for that, you could create a linkage that allows you to add a bob weight inside the fuselage to use a larger moment arm with less weight on it to counteract the weight of the heavier rear panel of the elevator.

Gerhard