Alright, this is what I ended up doing: I shortened the existing mount and made this "adapter" which simply slides over it. All I have to do now is reinforce it using a few pieces of triangle stock and I should be good to do.

I now have a new problem: When trying to install the servos, I was surprised to see that there was only a very thing strip of plywood available to screw in the servos. This problem became somewhat worse as I had to make a "notch" to allow the servo wire to clear the opening. If I tried to screw in the servos as is, I would likely split the strip of plywood or at best have a very weak installation which would eventually let go. Interestingly enough however, there is plenty of room on the sides of the servo. Only if the mounting wholes were there... To make it easier to follow what I am saying, I have drawn lines to illustrate where the plywood is under the covering.

Any suggestions on the best way of properly securing the servos in the wing?