Things to check:
Does your radio even support V-tail or elevon mixing? If not, you may need to pop for a v-tail mixer that goes between the receiver and servos.

ANY set of servos from the same manufacturer will work, you just have use the servo reversing function, then swap the servo plugs in the receiver.

.75" is a huge throw for elevators, you must have your CG pretty far foreward. As previously suggested, 8" back from the nose is a good CG. Most 'chevron' type wings seem to work well with a 2-to-1 ratio of aileron to elevator throw. Adjust the elevator trim until you get a smooth, fast, flat glide. The faster you fly the more efficent it will be.

And something to consider: Maybe your hill just doesnt provide enough "oomph" to get this thing dialed in. If there is a steeper, windier hill to fly at, try it. Good lift is a treat.