Disable Macbook internal display

Why not put a small and not super powerful magnet on the specific area of the sleep wake sensor so that the system thinks the lid is shut?

• https://support.apple.com/en-us/HT203315

With power and keyboard connected, you'll have it running in closed-clamshell mode with full benefits for your use case and no need to move the actual display.

There are amazing USB-C pass through docks now - some that sit flush and others with a stand off cable so you can get around the limitation of only having two ports if that's the only sticking point for clamshell mode.

• https://www.indiegogo.com/projects/hyperdrive-world-s-1st-usb-c-hub-for-ipad-pro--2#/
• https://www.amazon.com/CableDeconn-Thunderbolt-Charging-Multiport-Adapter/dp/B07BK4TRG8/

The good adapters are still in the $50 US range, but the knock off ones are rapidly approaching $10 so you can pick metal or plastic and your warranty / support model of choice if you run out of ports.