I really like this idea and had some similar already.
However, XML changes I make work with all "official" skins.
Maybe one could have different XML and SKIN mods and the XML mod defines with which SKINS it works.
eg:
"default" layout (XMLs) -> works* with skins group: "default"
Arerano layout (XMLs) -> works with skin group: "default"
Tuathanach layout (XMLs) -> works with skin group: "TuatanachSkin"*
*works with can also be taken as "requires"
*name it as you wish.
Or maybe the other way around:
skin X NEEDS the Y-compatible XMLs
Y can be "default" or some "custom name".
the XMLs name could even have some version number included which can be bumped in case the XMLs change in a way which would lead to bugs with "old/incompatible XMLs", then refuse loading them.
I am tired.... hope I expressed it well enought
