Having been involved in numerous instances of either loading, or unloading, locomotives (and occasionally coaches) over the years I can quite confidently say that most of the people who do this for a living are very professional and make it look easy.
In the UK it seems that most hauliers have at least one trailer with rails flush with the deck and trailer lengths vary greatly. The longest rig I've had anything to do with was 105 feet long (it had an extendable trailer) which was reversed over a bridge when loaded because there was nowhere to turn on the other side - this feat required use of rear steer - and the skill of the driver was amazing.
Unfortunately I have few photographs of these moves - and those that I do have are not yet scanned.
G