Running generator at night while sleeping?

I have run my generator in my toyhauler for a solid week. it is mounted under my bed in the front of the trailer. the exhaust sticks out past the trailer a couple of inches. I have never had my co detector go off, or had any problems. they are designed to be run to power the unit.
the only question I have is why do you need to run it at a park? dont you have hookups? I understand running it on the road and while boondocking.