True! A tablet and an ext-keyboard do a much better job (Although I wrote bag.sh out of boredom while stuck in a beer-less airport waiting for a delayed flight; I hope I won't have to actively plan for this setup again)
I have a stack of Thinkpad Tablet 2 bluetooth keyboards (though it's getting a bit low, will have to find somebody on ebay or whatever that still has some again soonish) - they're capable of being paired to more than one device (I also use them with the tablet half of my Helix 2) and have a built-in stand which takes my 8" tablet just as well as it did the Tablet 2 itself back when I was using that.
So had I ended up in the same situation as you I would probably have done similar, but with an added undercurrent of "Matt, you idiot, how did you manage to forget to put the keyboard in your pocket before you left?!"
(still a neat hack on your part, mind, no question there, but I'm very much glad I've optimised by standard "leaving the house" loadout so inflicting the same thing on myself is at least *less* likely ;)