This topic comes around regularly. My own experience involves passing a test with an unladen flat 28’ single axle trailer drawn by a beaten up wreck of a unit with a 4 speed “straight” box.
From there I’ve driven most gearboxes out there and certainly much larger trailers and abnormal loads. Extra training? Zero. Common sense? Plenty. It really isn’t rocket science.
Without a doubt, it’s easier to pass on auto. At first I thought the powers that be had lost the plot. But, after thinking about it, I dont see the issue.
Drivers now have the added bonus of Google in their pocket. 45 years ago that was unthinkable.
Any help a new driver can get is great. The point ROG makes is spot on. With so many variances of gearbox, it’s not likely you’ll get to learn on one that you’ll be driving next week. Ask another driver, ask Google, speak with your trainer.
Good luck all, Pete 