Math on FLAGSTAFF Weight, doesnt add up?

[kevin]

Hi folks! Semi-Green Newbie in town. I just got my truck which I made sure wouldn't hinder what I would want to tow. In addition, I'm only looking at Lite trailers because I really want the truck to perform well and last and want the smallest length so its less an issue in some of those cramped corridors.

Now I am either confused on trailer weights or manufactures are not worried about what they put on the streets. Any help in deciding which is which would be helpful.

I'm looking at a 2014 Forest River FLAGSTAFF CLASSIC SUPER LITE 8528RKWS. The seller states the GVWR as 8950, Dry as 7513 and liquid capacities of 76 gallon grey, 40 gallon black, 43 gallon fresh water and 60lbs propane.

Seems to me in a best case scenario given liquid weighing 8.36 pounds per gallon on a good day I'd be lucky to have 400lbs left for cargo. I am looking primarily at boon docking and this seems well equipped except for cargo capacity.

So, am I missing an important point? Just seems illogical anyone would build something with little room for cargo that sleeps four people.