We almost always loaded over the side, whether it was a Drott, a D8 or a 22RB. Some times if it was a short move we didn't even bother to turn the navys on the bed, and carried them cross carrage.
Sometimes with a 4 in 1 shovel, if it was a bit steep getting on we would hook the clam over the far side of the trailer and pull it on.
There was good reason for side loading in those days!!!
There were no hydraulics on the trailers.The trailers were lifted with ratchet jacks and 5 ft. bars to release the weight off the 2 pairs of back wheels, which were then manhandled out of the way.(impossible on a slope)
The trailer was then lowered to the ground with the ratchet jacks to load the machine and the whole process reversed to replace the wheels.
I,ve even had to block the trailer and use the loaded machine (22RB) to lift the wheels back into place on one occasion when I had to load on a gradient. (Good job there was nothing overhead). Of course unloading would be a reversal of the loading procedure.
Everything was much the same with the first of the knock out neck trailers too, they also required manual jacking.
Thats why everyone loaded over the side whenever possible. Saved a lot of work!!!