The classic log trailer in the Pacific Northwest is known to the regulatory authorities as a stinger steered pole trailer. As you can see from the series of photos here, it makes use of the rear overhang of the truck to swing the 'reach' as its called instead of a 'tongue' as you go around a corner. The trailer is actually pulled by the logs, and you can see the round part of the reach near the pintal is actually a telescoping shaft inside the reach called a compensating head. When you turn it has to get longer. The effect of this 'steering' is that the trailer wheels follow fairly closely to where the truck wheels went. How closely depends on the ratio of the length of the 'stinger' as measured from the pivot point on the truck---usually the center of the tandems, to the hitch as compared to the distance from the center of the trailer tandems to the hitch. If those distances are exactly equal the trailer would necessarily follow precisely in the truck tracks. Practically speaking most configurations used have a some what shorter stinger. This means that the trailer wheels cut the corners some, but radically less than a classic semi-truck. This is a major benefit not only on the highway where it is possible to keep the truck and trailer on its own side the road even on a windy road, but is also invaluable on crooked narrow usually 1 track logging roads out in the woods.
This simple reliable technology allows for quite long loads to proceed down quite crooked roads. The logs shown in these photos are close to 50 feet long, pretty much the outside limit for a semi truck, and even at that, the trailer is all over the road on short corners. Shown here, this truck has been steered as short as the front wheels will turn, yet the trailer wheels are only cutting the corner a couple of feet. In Oregon and Washington state this combination can be used to haul logs or poles with out special permits in most places for a total vehicle length of up to 75 feet. Poles, as in power poles, are routinely hauled with permits and flag cars up to 110 feet long.