Last train to Durango question.

I was looking through the posts that Russ posted about the last "freight" to Durango in Dec 1968. I am fairly familiar with the run, but does anyone know why there were 3 cabooses on the train? One caboose (0540) belonged in Durango, and was necessary for the westbound crew. One caboose would be necessary for the trip back to Alamosa with 483. IIRC they picked up some gons of company coal at Sublette. So the 3rd caboose is the question. Did an extra crew tag along to prevent hours of service violations? Can a crew ride in the caboose an be considered "not working" like team drivers in OTR trucks? I am not completely familiar with the laws then (or now), or what the D&RGW practices were regarding hours of service. Either way it must have been a surreal ride.