Sorry for the late response, I just noticed the notification of your message. The generator is pretty loud both inside and outside of the van. If you're running your a/c at the same time it won't matter too much because the older a/c units are super loud too. The generator does run off the chassis tank fuel.
If I can answer any other questions please feel free to contact me.

Hello Chris; Thank you for your response to my forum inquiry. You mentioned that you have the K Travato. We are still trying to decide on generator or lithium. Is the generator very loud? And, it runs off of the gas in the tank and not the propane, right?