Wordy - If I read your prior post correctly, you are joining the vatail servos with a y-connector, right? If that is that case, you will not be able to use any rudder function, as they will both move in the same direction all the time (if they move in the opposite directions, perhaps you can use the opposite servo horn on one of them, or use a special Y-connector as Papa J suggested.
If you only have 4 channels, and can program for a V-Tail, I suggest you use the Y-connector on the ailerons, and use a separate channel for each of the two vtail control surfaces (one rudder, one elevator.) If you find that the tail does not perform as expected, switch the rudder and elevator connections.
Optimally, if you can program for VTail (built-into your radio), and have 5+ channels, here's the configuratrion for a Spektrum setup:
Right wing - Aileron
Left Wing - Aux1
Vtail1 - Rudder
Vtail2 - Elevator
Vtail1 & 2 may need to be swapped. When you pull back on the elevator, both Vtails go up. Rudder left - left Vtail goes up, right Vtail goes down. Rudder right - vice versa.
Potential bad news - If your radio is the CT6 equivalent from Hobbycity:
If specifically states that is is unsuitable for mixing or vtail. In that case you are definitely limited to coupling the two vtails together (as elevator only), and using the ailerons to turn the plane. Perhaps you already knew all this!
Hope some of this may help...Chris