That's not a reliable solution. It will only work if the resolution does not change on the primary monitor. In a real world there is a significant chance that one might use a different resolution when playing a certain game - let's say, and at that point all the hard work of setting up a desktop mode display goes down the drain. Usually this happens on the more demanding applications for which you need to drop the resolution ion order to achieve decent framerates.... which are actually the more important situations where you would want to monitor things
I did actually spent days to set up different desktops for different resolutions and automate changing them via global profiles, based on what application is running. While achievable, it is incredibly time consuming and fragile. Having proper multimonitor support would solve all this hassle, and will definitely motivate people to run aquasuite for monitoring purposes on small monitors as their primary solution.