Our kid is nearly 3 years old and really enjoy eating. We have dinner together when I come back from work at around 20:00, and he eats a lot. His belly is really full then. Recently he wakes up during the night. I wonder if it is a bad thing to go to sleep with the belly full.
My children all slept fine after late-night feedings, and so I don't think this is any kind of danger or contributor to his waking up at night.
His schedule of bathroom use might become a little unusual, but kids are resilient.
Adults often go to sleep with a full belly. I am not sure why that would be waking him up? Certain foods can make sleeping more difficult, but assuming you are having healthy meals I don't see this as a problem. Three year olds often wake up in the middle of the night.
I would evaluate for night tremors.
Three year olds are just developing the idea of what fear feels like and often that makes them wake up at night.
I wouldn't worry about the food and the full belly, nor really the waking up, I would more deal with the situation until he stops waking up.