Re: tow vehicle
John's statement could be correct, but it also could be a little misleading. It depends on your particular trailer. For example, I own a fifth wheel that has a GVWR of 14,000lb. (2 - 7000lb. axles) The UVW is 11,468lb. I have scaled it and it now weighs 12,000lb on the dot. That is my loaded weight, food, clothes, etc. I will NEVER put another 2,000lb. in my trailer and believe me, it is loaded.
I have another trailer on my lot with GVWR of 14,000. UVW is 11,094. NO ONE will put almost 3,000lbs. in that trailer.
Take your trailer to a scale. You can find one at a truck stop. I use a farm feed store. They don't charge if you just drive over the scale and read the display. You will realistically add around 500lbs. to the empty weight. It is best to have a vehicle that can handle more than GVWR, but I don't necessarily use it. I am NOT suggesting using a vehicle too small, I just don't always use GVWR. Scale your trailer and you will know what you are dealing with.
It is also best, and legal, to travel with empty tanks except for fresh water. Think about having a wreck with sewage in your tank. Did you know that MILK is considered hazardous waste by the EPA, if spilled on the ground? Think about sewage......
Please dump your tanks before traveling. Fill with water to aid dumping if necessary.