I understand why it’s not good to do this. I was surprised that it was common enough to get a mention in the manual.
In the late 60s, my grandfather had an old Chevy sedan (probably early 50s model) that he chopped down to open the back seat and trunk. It was kind of a proto-El Camino. Anyway, he had a steel rim and tire with the correct bolt pattern that had an extension that closely mimicked the belt drive pulley on an old tractor. Anything you could power off a belt could be powered off this set-up, including saws and pumps. The pulley was not something he welded up…it was a common commercial product. And I distinctly remember that he only used a single jack to get both rear wheels off the ground.
Yes, my grandfather had such a wheel adapter also. He used it to pump river water for irrigation. It was an old Model T or something that had the entire body removed so it was just a frame with engine and front seat. But you could put the regular wheel and tire on it and drive it to a new location.
There was a lot more load from the emergency lights package back in the day; incandescent bulbs & rotators &/or strobes in the light bars; everything is LED nowadays so even though there are more lights on a modern cop car there’s much less draw from all of them.