My suggestion is to make servo covers.
You will need a two liter plastic bottle that has smooth sides.
You will need to find or make something to use as a mold.
The objective is to form the plastic into an oval or rectangle with a lip all the way around.
Depending on how far the servo sticks out of the botton of the wing will determine the thickness of the Balsa for the next step.
Find a piece of 3/8" thick Balsa and cut it so it is about 3/8" to 1/2" bigger than the servo when the servo is in the middle of the block.
Carve the block into an oval and round all of the edges.
Cut the top and bottom of the bottle off so you are left with the flat middle part. Cut it in half lengthwise.
Put on gloves or get an oven mitt, use you heat gun and form the plastic over the Balsa mold you made.
The plastic will conform pretty easily so don't overheat it.
When you are satisified with your handi-work cut the oval out leaving enough of a flange to put screws in to hold it on the wing (you can aslo tape it on the wing).
Cut a hole for the servo post to fit through and you are in business. Scuff it up and paint it or use peel-n-stick covering, I doubt if you can iron covering on without deforming the plastic.
Adjust all measurements to fit your particular application.
Good luck.