I don't see where there's any "confusion" about GVWR. Honestly, it's very simple.
GVWR is the gross vehicle weight rating. It's the maximum the trailer can weigh. Regardless of what "cargo" is onboard that increases trailer weight, when the weight gets to the maximum (GVWR) then you can't add more weight.
Start with empty tanks and you can add weight "UP TO THE GVWR"
Start wtih full tanks and you still, "can add weight "UP TO THE GVWR".
In the first situation (empty tanks) you have more "weight to add" but the GVWR is the same in both situations. Once you hit GVWR, you stop adding weight....
In this day and age of half ton trailers, heavy half trucks, enhanced towing packages, ultra lite trailers and all the other "smoke and mirrors", people get "sold an image" or "see what they want to see"....
No matter what weight you start with, empty tanks and lots of cargo capability or full tanks and reduced cargo capability, when you get to GVWR, your trailer stops being "Cinderella's carriage" and becomes "just another pumpkin"...
If the GVWR is 10000 pounds, and the empty trailer weighs 7000 pounds, you can add 3000 pounds to the trailer. Matters not whether it's 1000 pounds of waste water and 2000 pounds of recreational equipment or no waste water and 3000 pounds of recreational equipment, once you hit 10000 pounds, you're towing a pumpkin at GVWR.
Looks to me like there's a "sudden realization that hit those Jayco owners"... They found out that waste water is cargo.... DUH !!!!!
