I’ve looked at what dex docs are avaliable on my local e-bay equivalent, and they’re more expensive with less ports avaliable (Usually it’s 1x usb c, 1x usb 3.0 1x hdmi). I want at least keyboard, trackball, and power bank for usb ports (I might need another one to power the display)

If you’re planning to have no background then eraser might be your best bet. But if you’re doing background it might not even be necesarry. The marks appear so light that if you draw over then, they’ll not be visible