Hi Emilie,
As you can tell from the opinions stated above, there is no right or wrong option here and whichever one you choose, the most important factor is that you are getting plenty of nutrition & fluids in during your treatment.
My wife is currently in her last week of treatment and has managed to get by without a PEG but the doctors are recommending a nasal gastric tube just in case as the few weeks after treatment are supposed to be the most difficult.
As we end the near of our treatment, we wish you the best of luck with your upcoming and encourage you to stay positive and keep one step ahead of the curb!