There was a time I had a desktop PC and a laptop for work. I loved my three-monitor setup but needed to use the laptop pc when attending meetings and working from other offices. It all changed now. My setup is a laptop with one external monitor and a mouse.
How it all started
I did not want to switch to my laptop as my daily driver until I went on vacation. Long story short, my wife made me do it; the story of my life. While on vacation, I needed to respond to emails and check on servers. We were staying at this gigantic Villa where the Wifi was decent in the lobby only. So I would go there when my wife was asleep to catch up on some work. There was also a monitor there, so I thought: why not hook it up? So I did just that. It was awesome. After I returned, I retired my desktop computer and used only my laptop with just one external monitor.
It looked something like this:
And it's still looking like that.
How it's going
The simplicity of this setup is why I like it so much. It also goes well with my daily activity. Even if I code most of the time, there is still a lot of reading involved. I go through posts and code for hours every day. I've noticed my posture changing when reading as opposed to coding. I use the mouse when coding, but I use both the trackpad and the mouse when browsing the internet. It looks weird, but it works. The best thing is when I need to leave the office, I have my familiar everyday keyboard with me. It is also clean, as my monitor is higher, and I use a 13" laptop. But it's no problem if there's a little overlay. Just place the monitor a few inches behind the laptop's display until you see the entire image on the external monitor.
Should you use this setup?
I recommend you try it. This setup allows you to focus more as there is just one monitor in front of you and still gives you the desktop real estate to add a video or some documentation on the laptop's display.
You might need extra monitors: you could add them on the sides of the main one.
All you need is a laptop with a decent keyboard. If you don't have a laptop, get a small display that fits nicely under your monitor. The vertical setup is worth it.