Interesting stretch goal you've got there! As a singer, I'd say you've got a few things to think about:
- Even if you have a phenominal recovery, you'll still be five days out from abdominal surgery.
- Maintaining focus, even staying awake, may be beyond you, especially if you're still on painkillers.
- Standing, if your role requires you to do so, will be difficult to do, and very difficult to maintain for the duration of a song.
- Breathing, let alone fine breath control, will be painful if even possible.
- Resonance. If your range means you sing at the resonant frequency of your chest, or those around you do, you may have a uniquely painful experience.
Best wishes, and if your director is willing to be flexible, and you feel up to trying, let us know how it goes. Best wishes to you and your recipient.