I know there's the difference between the native hottentot dogs and the rhodesian ridgeback, the ridgeback was developed by europeans using the native dog and crossing it with their own hunting dogs, like you said including scent and sighthounds, stock dogs and some mastiff and bullbreed, but the resulting lion hunting dog produced very rarely would have went over 60 lbs (still considerably bigger than the native dog they descended from). Quickness and lateral movement being critical like you said, as well as limitless stamina and heat tolerance, too much size is going to result in sacrifices being made in all of these departments. The ideal size is gonna be around 60 lbs. Like most curs and hounds used on dangerous game today.

I don't think anyone is making rhodesian ridgebacks artificially small, that's just not what the show dog world does I think we should all know that by now. No I think the leaner lighter ridgebacks you see are most like the original colonial crossbred hunting dog of southern africa that the "rhodesian ridgeback" breed is an homage to, and the very large ones you see are a typical show-dog world exaggeration, with the help of recent outcrosses to bullmastiff and possibly dane. Breeds which may have went into the old school hunting dogs as well, but didn't influence the size in any way which would have been detrimental to the role asked of them.