On straight track, you should have no problems coupling the cars by pushing them together until coupled. Wide curves are needed for full length passenger cars.
To run passenger excursions on my layout, I picked up a pair of Proto 1000 RDC’s, no diaphrams to worry about here and no need to turn the loco at the end of the line.
I have both problems. Have a hard time getting them to couple, but then once they do it is a nightmare to get them to let go. It is times like these I wish the Kadee magnets were still in the track.
I also have a cure for, “The Kadee Magnet that Isn’t There.”
I buried steel plates (chunks of tin can) under the ties, and only place the magnet when I want to uncouple at that spot. While the original idea was to save a couple of bucks, it sure does cut down on unwanted uncouplings.
Then I discovered a spot where I occasionally needed a magnet, but didn’t have a buried plate. The solution - drive two parallel rows of flathead nails into pre-drilled holes. The nailheads are set just below the tie tops. The magnet (permag delayed uncoupling type) snaps down and stays put, and the Kadees uncouple as designed.