The excellent article in the July 2007 MR on servicing cabooses reminded me of a caboose service truck that I helped design for Conway Yard a year or two after the Penn Central merger.
The purpose of this truck was to take the servicing to the caboose instead of moving the caboose to a service track. This allowed cabooses to be moved directly from the receiving yard to an outbound train. PC spent a small bundle on this truck but the savings more than paid for it and my salary for a couple of years to boot.
I unfortunately don’t have any pictures of this truck but my memory is that it was built on a Ford cab-chassis with dual rear wheels. The body was a box approximately 20’ long and of normal height (12’ ?). I do recall some concern about the height as there was at that time an old stone arch underpass at the west end of Conway that the truck had to navigate to get from one side of the yard to the other without making a detour of several miles. The only thing unusual about the truck from the outside was a platform of open steel grating (like a rook walk) on top of the cab and a narrow ladder to get to it. From that platform, the windows of even former PRR cabins (with cupolas) could be washed.
Inside the truck was everything you could possibly need to service a caboose. With the variety of flammables (good sized tanks of fuel oil and kerosene) and a couple of boxes of fusees, the thing was probably a major fire hazard but I never heard of any problem along those lines.
So don’t feel guilty if your model yard doesn’t have a designated caboose service track. Just put a platform on top of the cab of a good-sized truck, paint and decal the truck for your railroad, and call it a caboose service