If I could, I'd have a 4x8 foot display with no decrease in pixel density. I.e. an incredible number of pixels.
Heck, why stop there. Give me a wall sized display! Phooey on laptops.
I have my MacBook Pro hooked up to a 4k external display, Microsoft Natural Keyboard (or whatever they are called today), and a nice big Magic Trackpad 2. I can undock it and have exactly the same system on the go. the MacBook Pro can drive multiple screens (2x4k on 13", 4x4k on 15"). You also use an external GPU over Thunderbolt 3.
What's the point of having a laptop if you can only use it with an external monitor, keyboard, and mouse? A powerful desktop is much cheaper, and you can stuff huge disk drives in it.
When I'm on the go, I bring a cheap laptop (in case of loss, theft, or damage) that doesn't have my whole life on it and mainly take a vacation from working. (And I'll use the time to catch up on my professional reading.)
Really hard to get myself to code on my laptop now.
i think you would find this setup to be really poor.
you need be within ~2ft viewing to appreciate the difference between 1080p and 4k at 24" diagonal display size.
sitting 2ft from an 8ft wide display will give you very poor viewing angles for the majority of the content. at greater distances than 2ft, the pixel density of a 4k 24" display become nothing more than waste of gpu, cpu and electricity.
As for discerning pixels, I know that the retina display is distinctly easier to read than non-retina (both from Apple) even though I could not see the pixelation on the latter. Watching video does not make much difference, but reading text sure does.