There were several trailers like this one -- called a "stacker". As you can see, this is actually a two level trailer that contained about 8 motorcycles as well as a living area in the front. The door doubled as a electrically driven lift the moved up and down to load the bikes. Amazing! The trailer was pulled by a full-sized Freightliner tractor.
Finally, we were very impressed with these two H3 45' Prevost coaches. Both of these pulled a triple axle stacker trailer like the one above and were beautiful (so were the motorcycles they unloaded). This motorcycle hobby is a serious business!