I have a similar setup but with 34” Ultrawide curved monitor as the main screen.
Like you, I rarely refer to the Macbook monitor and spent a few weeks using it in clamshell mode … and didn’t really miss it to be honest.
What works the best for me however is to try and be disciplined and use the Macbook monitor as a reference display (in my case, Omnifocus and today’s calendar / schedule). … and try not to touch it. It doesn’t always work and I sometimes ‘park’ a window on there when I want to focus on a single task on the main monitor but - having played around with different setups, the reference display appears to be the most practical approach.
Nice pond by the way. Also, in my nosiness, I noticed that you and I appear to share an interest in all things Oracle
I have settled with my Air below the main screen and use it only as a reference monitor. After years of experimenting, I’ve decided I’m definitely a one-monitor kind of person for my task at hand, but a reference monitor is handy at times (basically, whatever I want to be able to glance at).
I never found Luna very stable for me. If my Air didn’t sit nicely under the main screen, I’d probably go with clamshell mode and use an iPad with SideCar.
I have almost the same setup as this. Keeping my Air below the main screen with half closed lid. I open and reposition the lid only if I need to make a video call. All the cable goes to the 24" 2k monitor.
It works for me with my Air screen tilted way back. Not an ideal angle, but it’s only for reference and works well for me. It also lets me tuck the Air behind the monitor, giving me space for my keyboard.