Kallem...

I only used one servo for the rudder. I used a HS5945. I think it gives about 150ozs torque on 4.8v (my setup) and about 180 ozs on 6v. This is plenty of torque to fly this plane under any circumstances. This will also help you keep your goal of light weight. Save about 2 ozs by the servo and another 1-2 by not needing another pushrod and servo extensions.

I've got about 30 flights on mine. The rudder is very powerful and I don't feel any need to upgrade the servo torque let alone go to a second servo.

I'm not sure why Great Planes recommends two servos but it really isn't necessary.

Thanks
Barry