In my case the "freaking me out" has a tendency to lead to endless rumination and analysis paralysis. The flat neck area will help a lot. Is it flat on the bottom too? A problem I had when I needed to do a rout on an ES body was that it was hard to immobilize the body because of the curve on the back. Even so, that was not as challenging as yours since I was just enlarging the rout, not creating a whole new one.
Even so, more work ended up going into the jig than into the cut ;-)