I agree with you making a good template is the starting point of a skinning project.
Time consuming at the beginning but as you well explained the only way to get proper skins in number when you want to cover each Nations / Squadrons / Service date.
I like to use
Paint
the Gimp Artweaver
Xnview (Very useful tool to convert all the picture file format with batch processing)
http://www.xnview.com/de/
I'm still working on Veltro2K's Alizé with the help of experienced moders Baffmeister for the FM's, JonathanRL for the specific Campaign and learning.
As example
4 different version of the planes for the French Navy x 3 Squadrons skins per planes 12 skins + one for the Indian Navy version + the Decals job (Template also needed)
+ 1 specific Hangar screen for each so I've made a template for the Hangar too.
+ The INI's work
and at least all the debug flights
The good thing I can ask to the 3D modeller to make the necessary change / the Bad thing 4 version of 2 LODs Family.
Without templates impossible to do with the RL issues
I'm just looking at your nice template and you give me some ideas thank you for sharing