What are the MPG- 181 water tank sizes, and how do they factor into the GVWR?

There's just shy of 1,000Lbs difference between the dry weight and the GVWR.

What are the water tank capacities, and do they consider full tanks into the GVWR?

Thank you

marc515, Gross Vehicle Weight Rating is the maximum that unit can legally weigh. It doesn't matter what makes up that weight, that's the limit. As I understand it, dry weight is as the unit leaves the factory, so it probably doesn't include any water, propane, or battery.