I haven't tried dual booting as I've never had the need. It's certainly doable on some devices if you wanted to do it this way (details to be found somewhere on forum.xda-developers.com) but I wouldn't bother and just install whatever UN*X stuff you need into Android (assuming it's shell-based).

Personally I find the 5.7" screen on my phone large enough for temporary work. The biggest issue is of course the lack of physical keyboard. One way to address it would be to get a BT keyboard -- something like the K480 from Logitech even includes a holder for the phone/tablet.

Or, you could SSH into the phone from any other computer you have access to at the moment: use Dropbear daemon as the server and set up public key authentication, keeping the key on a removable USB device you carry for basic protection against keyloggers.

There's also the "Hacker's Keyboard" for Android that emulates a full keyboard with all the modifier keys, and could work for very light, casual use although if you have to use it frequently this way it's obviously beyond inconvenient.