If you "Back tape" as in this photo when you shoot the color on the outside of the cab at the line I show in my last post, it can be made pretty hidden if not completely. "Back taping" is when you don't lay the tape down flat creating a hard line. You roll it or you use a foam aperture tape which is a 1/2" or so foam tape. What this does is provides a soft edge of paint that you can clear over. It isn't quite this simply it would take a little practice to dust paint at this area so you don't end up with a hard line but it can be pretty effective.
3M aperture tape.