Everyone runs into the same problems you have.like anything else, the more you do the better you get at it.Seems like a guy always has to move some nails.
If the pelt will not reach the next line , you can go part way, the only thing with doing that,you must make sure not to lose your shape.
Lips and nose can be removed without hurting the pelts value.So unless you are planning on giving that beaver a smooch, the lips arent needed lol.
Tom