[mechanical_fish]

This is fine advice, but you're burying the lede:

There really i no ergonomic way to use a laptop that doesn't involve at least one of an external keyboard or screen.

Amen. Laptops have lousy ergonomics. Get an external keyboard, and/or a portable external keyboard, and/or find some way to prop up the screen, and/or get an external monitor.

[jvdh]

I completely agree. Make sure that the top of the screen is at about the same height has your eyes when you're sitting upright. That's the best ergonomic height for a screen and will prevent you from slouching.