factorization of skin
 

aircraft variants have the same structure, and the skins are compatible.
with this little script you can make to the skin in a single folder (the one you want) and all variants will have it.

link :
http://cliffsofdover.fr/tuto/skins_f...1.02.14821.zip
sorry it's in french but friendly use:
just most have seven ( or maybe vista ) and execute .bat in administrator mod