I have figured out why only the float plane accepted multiple skins settings via cfg file. Any plane can be set similarly; the trick is renaming the main material of both full resolution and LOD GR2 models, from 'skin' to 'cfg#TXRskin'. This is easily done through GR2 Editor. No need to clone the model, nor to create a proxy unit. I was going to do it with your version of the Liberator, but it seems corrupted (no version of GR2 editor seems to open it). I have nonetheless made a testing mod which makes your new textures available in game:
http://www.mediafire.com/?tzrhxcgw0oa1tdy
Included in the mod are three single missions for testing different scenarios. They show some limitations of the game, relative to the handling of multiple textures by the same GR2 model:
- if many proxies of the same model are mixed together, only one texture is shown, no matter if they are set to use different skins.
- multiple texture definitions applied to the same roster entry are ignored, even if they have different date settings. Only the first texture definition is applied in single mission, no matter its date. I only hope that in campaign things are different.