Too late I saw your message!

The socket for the servos WILL accept a larger servo, but you still have two problems going this route...

- Weight, now you are talking about a significant amount at the tail.
- You still need a reversable servo, which are significantly MORE expensive in standard sizes.

The cheapest way of doing all of this, that I could find, is what I indicated.

Even if you used inexpensive microservos, you would still need a reverser, and you would have to open up the already glued fuselage to fit a second extension line.

In addition if you opted for mixing two servos on separate channels you would minimally need a different TX.

So either way you end up spending more than the cost of the two Spektrums and programmer.... and the latter is quite useful in the future...

After discovering all of this I went ahead and ordered 4 servos and the programmer, knowing that I WILL use the other two servos at a later date along with the programmer.