Thanks guys.. I think I got a working solution. Still couldn't ever find anything in the manual, but I managed with what you guys said in the thread and some scrap plywood.

Thanks for the suggestion about the vertical fin.. I think I'll definately be putting those braces in now.

Here's a related question just for curiosity's sake:

The hole in the wing is only about half a centimeter short of being able to fit two servos in there instead of one. A couple of you guys mentioned that you're are running independant servos for their ailerons. Is there an advantage to having the servos mounted in one place instead of the other? (like one centered on each wing half in a hatch like condor mentioned, or both side by side in the middle like FHHuber? Or is it just a preference thing?

I was just thinking that it would be very simple to add a 2nd servo later if I wanted by moving the one that's in there over to the side, and cutting the hole just a tiny bit bigger.