I wouldn't be so sure
I've got a long way to go.
I'm just curious because it seems to me that you could put the valve between the overflow and the skimmer, and that would adjust the water level in the overflow, but then you might need a second valve downstream of the skimmer to adjust the water level in there. If that valve is set to a position "more closed" than the upstream valve then it becomes the master valve controlling both overflow and skimmer water levels. I guess if the skimmer was set low enough then this wouldn't be a problem .. ?? I'm just trying to wrap my head around what would happen. Would one valve downstream of the skimmer suffice do you think?