Jon, I would strongly recommend that you consider the peg, you only need light sedation to put it in, it takes maybe 5".
It's small so you can't even notice it. As the others have said you need to get lots of calories, fluids, and nutrients in order to stay healthy through treatment and to heal. You will be healthier and recover quicker if you are in good shape nutritionally. Your throat and swallowing will be affected and it will be extremely difficult to eat and drink enough . My husband didn't want one and thought he could tough it out, by week three he was a hurting puppy and wgt was starting to plummet so he got one, but not willingly. You will need it after treatment is over as well, The weeks after treatment seemed to be the toughest.

Just be prepared that you probably won't be able to work every day towards the end and even after treatment, this is grueling treatment and you will feel like hell. If you're teaching you will be exposed to all those kids with all kinds of nasty bugs, (not sure if you have the H1N1 over there) but you need to limit your exposure since you will be compromised.

Good luck, start fattening up now. you'll get through it