Sorry for your wife, but I think building this feature would be a mistake.
(For the record - apologies to people with no willpower - you could presumably cancel it by revoking the app's Twitter access)
But you can't be given too many options as morning-brain will do anything to stay in bed.
Tweeting a photo may be a bigger motivator than just text (guessing this is not a current feature based on the screenshot provided in app store.)
Would have to be careful about becoming the "Naked photo tweeter app" though.
At the moment, a viable cheat is faking location on your mobile device.
What we thought of doing was your submit someone you wouldn't want to tweet and then have an account (the punisher account) tweet them the message saying it was written by you.
When we were at university we had it running on the machines there and it would just wipe your home directory or email your professor - harsh times but good times.