Hi Burrman,
Well separate would indeed create a bunch of questions. I tried to trim the body in half, duplicated and shrinked the copy, then joined the outer body to a solid again, but didn't come much furhter with the copied inner shell, Guess you cant flip the normals? That could other wise maybe solve the problem, except there would be a little gap between the two parts, but that I could live with.

//Oskar