Bob: Those aren't my cars, just a convenient pic that shows the distance between cars. I purposely chose cars on eBay that were already repainted, had major rust, etc. for a ground up restoration (e.g., sandblasted all the tin). More a renovation as I'm not using original Lionel colors. I passed on deals because the original was worth saving for somebody.
Doc: The CP-7: The end is bent up, inserted through a slot in the floor of the chassis, and twisted to keep it in place (left, below). I was thinking more of a new pivot point pulling the coupler in tighter (right, below). But the bend in the CP-7 doesn't allow much swing before hitting the chassis.
I think the CP-9 is flat (pic below -not sure). Without the bend, the CP-9 will allow a wider swing pulled in closer to the car than the CP-7. But I don't know how the shorter swing will react on curves. And I'll need 14 to 16 couplers. That may nix the whole idea.