It's not impossible to eat healthy while on the road, you just need to do your best to make good choices when you can. Don't try to be perfect. No one is perfect. As long as you are mindful of your portion sizes. You'll be fine.
One thing I will say is watch the muffins at breakfast. Even a small one could contain as many as 500-600 calories. Check to see if there is a grocery store near the hotel and buy some healthier foods there to snack on if there don't seem to be any at your hotel. Most hotels do serve fresh fruit. So, have some fruit for a snack. You could bring along some granola bars of your own choice. But if you don't want to carry them on the plane, find out where the nearest grocery store is to pick up supplies. Many hotel rooms do come with a small frig and even a microwave.
I'd say if you're worried about what you'll at the show, bring your own food. Also, convention center food tends to be really expensive. So, if you don't have an expense account, another good reason to check for local grocery stores.