We consider all RV trips as somewhat of a "mini-expedition", and as such leave home with all tanks full that should be full and all tanks empty that should be empty.
We never know what situations can occur out on the open road and often don't know where we might be camping day by day. We leave home in our Class C with: 45 gallons of fresh water, 60 lbs. of propane (15 gallons in an 18 gallon tank), 55 gallons of main engine gas, extra gas for a portable generator, extra propane for a portable firepit, an empty 29 gallon grey tank, and an empty 39 gallon black tank. Plus we usually start out with at least 48 bottles of drinking water. We of course sometimes travel between campsites with all tanks full that should be full and all tanks that should be empty not empty (partially full but not yet emptied.). All of this is in addition to a whole of bunch of gear in internal and external storage areas.
However we did anticipate this RV'ing style when we bought our Class C. It's a small 24 footer, but built on the optional-at-the-time E450 chassis. We probably have at least 1500 lbs. of additional load carrying capacity when we leave home. I've not noticed any negative affects in handling of the RV whenever it's loaded like we do - but still well below it's design maximum. In fact, it rides better with this much weight loaded on it.
The freedom that a high margin of weight carrying capacity gives is what comes from what I call having a motorhome built with "chassis overkill".