If you are speaking of the problems that occur during a reverse move, I've tried weighting some of the trailers without much luck. If I add any more weight, I'm afraid the rails will buckle, as much as 5 1/2oz. I think the problem is inherent in the cars. I've given up doing reverse moves with long consists.
When my layout is set up to accommodate modern day rail service, I have over 120 Triple Crown trailers. I have changed my wheels to Atlas metal wheels. Filing down the frogs also helped. And of course, using premium switches like Peco, Walthers/Shinohara, and Shinohara lessened the problem substantially.
Changing wheels helped some. But I've relegated my self to no reverse moves with long consists. About 10-15 cars is about all my switchers move at one time.
For weight I added the red modeling clay and florists' clay. I think I got it at Michael's or Hobby Lobby. I've tried Pla-Doh, but it isn't quite dense enough to add sufficient weight. Florist putty, or clay, seems to work the best.
My Dad used modeling clay and BB's for many years. He would press the BB's into the clay. This procedure worked very well in cars like covered hoppers. BB's are MUCH less expensive than filling a car with clay. It's a method that has stayed with me for many, many years.
Bob