Similar mesh types (gameSpace)

I've got two similar mesh types that will use the same skeleton, with having only one difference in the initial mesh shape pre-skeleton attachment.

However, my mesh seems to need a lot of muscle editing once the skeleton is attached. I wanted my two meshes to be the exact same with one difference between them; all animations and the skeleton will be the same.

If I have to do a lot of muscle editing for both (the same muscle editing for both, at that), it would be really inefficient overall.

What I'm looking for is a way I could set up a mesh with a skeleton and all muscles edited, but be able to make changes to the mesh without affecting the muscle and skeleton set-up.

Is there any way I could do this? Or is there another way or a better way to do it? Or have I been somewhat unclear about my explanation?

Thanks.