You mean like this? http://improveverywhere.com/missions/the-no-pants-subway-ride/

Sounds like fun!

Sorry for the self-reply - I didn't fully read the summary the first time, and didn't notice the part about the thumb. The datahand does in fact have a number of keys for the right thumb to use - but you could use a custom firmware that has a different keymap that doesn't use those keys. I would be happy to help modify DHFirm for this case.

If you have the money and don't mind a bit of a learning curve, datahand is definitely the way to go. Although, I wouldn't buy a new one myself at the current price. But you can find used ones on ebay occasionally, that go for about half of what a new one costs. Which is admittedly still a pretty big chunk of change for a keyboard. But they are much, much, much easier on your hands.

Also, if you want to geek out on it, you can check out my alternative firmware - http://github.com/JesusFreke/DHFirm