Cool mesh! I like the idea of replacing the astronaut meshes.
Actually, there are 2 versions already on the Gemini addon, one is very rought and the other is nicer, with the astronaut's face visible inside the helmet.
The better version is visible when on the VC. Exterior views use the basic version.
I think that with some adjustments to scale the better version could be used for both interior and exterior views.
I tried using the the internal mesh a while ago as the EVA mesh by simply copying "gemplt.msh" and renaming it "gem-eva1.msh". Unfortunately the "bottom" of the mesh does not appear to be complete so you can see through it, but it was designed to be viewed in the seated position so I definitely can't complain. Currently I'm using the mesh by Rodion which is beautiful and breaths new life into Gemini. That said I can't wait for Saturn V's version.