Here’s a Roco WWII era M4 high-speed tractor weighing about 15 tons. They were primarily used to pull large guns and had little use in civilian service but could be purchased for very little, especially to small governmental agencies

This scene shows it being delivered from a surplus sales outlet halfway across the country by rail to a local community rescue and public service agency. The tractor has been painted gray and red rather than the normal OD which helps give some color to your scene. The local trucking company borrowed a trailer from the nearby contractor to unload and deliver the machine to the town garage.
The truck is the popular Autocar DC-95T tractor with a 160” wheelbase pulling a Rogers removable gooseneck drop side trailer. When building the kit #95046 the third axle was not installed making it into a 35 ton trailer very popular in the 1950s.

Notice the blocking needed to get the tractor over the rear tires and down onto the deck. Also notice the planking on the drop sides because the tracks are too close together to straddle the center beam of the trailer. The drop side design was to carry carry a crane/shovel as low as possible but in this cane there is no height problem.

Both images show a typical Autocar tractor, 164” wheelbase and a custom built headache rack for holding chains and binders. The rack was made with 0.060” upright styrene channel beams with horizontal 0.040” styrene rods. Check to see if I’ve uploaded other pictures of this truck that shows the headache rack by doing a search (on this web site) for 101520 which is the serial number I’ve assigned this model.

The first photo shows a 50 ton drop center trailer with 11.00-20 tires so the load must be blocked toward the front.
This trailer best represents a reworked Rogers with a gooseneck that is too high for a truck fifth wheel because it was designed to be used with a “jeep” dolly. That is the reason for the 7” lift under the gooseneck.

The second photo shows a level deck trailer with 11.00-15 tires. In this case the top of the load is just a little over the 13’-6” minimum bridge clearance. the first picture shows aa load a little more than a foot higher.