Two servos is the way to go. You can link them with a Smart Fly Equalizer II . It is a very small and light chip that each servo plugs into and in turn plugs into one channel of your receiver. You can individually set the end points and sub trims using the easy to program dials. Only costs around $40.00. I've been using one for the past two years with absolutely no problems.

http://www.smart-fly.com/Products/Eq.../equalizer.htm