Good luck, aint gonna be easy, doesnt come more flimsy than MSO5000series backcase even when pursing the smallest VESA Std (75mm -2) and Not even sure it will be sufficient to DIY-metalplate it behind the plastic, perhaps..
https://youtu.be/P5faiEUXbGg?t=465Maybe you can use some top and bottom grapper approach, bull will complicate it both lookwise and design but would love to see ur final build..
Used lot of these monitorarms back, in the day for day trading screens, nowadays I tend to use one big 55" LG OLED TV as a deskmonitor for all the tradetickers and qoutedepths and its a blast to game on or watch movies..