I would think the answer, is that yes a 53 streched out is easier than a 20' pup. At least to me. The only other consideration is swing room for the long hood I like to have.
Two receivers in a row thanking me over and over because "it's so nice to have a guy that knows how to back up". Then at the very next shipper I'm pulling up six times to hit a hole and got out of my truck red faced with embarrassment, I get out to the dock workers telling me to move because this is a step-deck dock. Jesus, I wanted to just drive away....
It happens. Just to be at the Airmail postoff off Normandy at LAX, these guys would swing in there and bam in the dock, just made it intimadating, but after a couple of nights of backing in to tight spots 5 and 6 times a night it got better. Line on the cement are a wonderful thing.
Harder isn’t the descriptor I would use. They just react faster so you just adapt your timing. Whenever I see a trailer wagging it’s usually because the driver is backing too fast to keep up with it.
In the height of my yard dog career, I got to the point where I could (and often did) back 53’ trailers into an internal dock, while talking on the phone and writing on my note pad at the same time. Around the same time, I once tried to show off to my neighbors by attempting to back my lawn sweeper out of the garage with my riding lawnmower. I embarrassed myself miserably.
I don't think any specific trailer length is harder than another. It's simply your experienced match to it. If you're experienced with pups, you're probably gonna struggle with a 53 and vice versa. One of the jobs I had in college was at a local general aviation airport and would move little Cessnas and Pipers around alot. There's a double reverse in the mechanics of doing that and can be tricky to get used to, but once you can do, it's easy. Try doing it without practice and some training, good luck with that!!! My opinion at least.