I tried a few things at the start of the local lockdown, and soon found that laying flat on my back was a bit impractical (this guy seems to have found some solutions which I consider too much hassle like the suspended laptop). Also I find that laying flat on my back puts pressure on my lower back, perhaps due to tight abductor muscles or something.

What I found was that with a couple of pillows on my couch, I could elevate my upper body in a gentle curve which resulted in my eyes being almost level but with no stress on neck or back (compare this to the guy in the article elevating just his head, which is too acute an angle and stresses the neck). At that point I just moved my monitor to various positions and elevations in my sightline until it seemed right. I had my mouse on a coffee table so that my arm was not elevated, and my keyboard on my lap (this part required touch-typing, otherwise I would have to keep lifting my head).

Once I found the sweet spot where i was relaxed but supported ( it wasn't that hard), I could pretty much work indefinitely. At that point the issue was no longer stress on any body parts, but the potential overall fitness degradation of lying down all day, which could theoretically be solved with regular breaks for getting up and moving around, but I was probably a bit lazy with that.