Thanks for your replies. I've done a little research on my own. Seems the "sticker" rating is GVWR or the maximum gross weight that the trailer can be, including cargo (in most cases...). That makes sense since with our minimal kit our trailer certainly doesn't "feel" that heavy going down the road. I'll weigh it with our usual stuff on board in the spring to be sure we are legal and safe.
Hints for lightening: By all means do not exceed either your vehicle's tow capacity or any of the load limits! But here are some things I've already done or am planning to do this spring to help reduce the loaded weight:
1. Drain our 10 gal fresh water tank and fill up at destination (save 100 lbs!)
2. Switch to a smaller 'house battery' to power new LED lights
and low-draw propane
alarm (had to anyway and saved 30 lbs.)
3. Switch down to a smaller propane
bottle - Our "20 pounder" weighs 40 lbs. Our normal summer needs are very minimal and so I am planning to switch down to a 5 or 10 pounder which weigh about 10 or 20 lbs full, respectively. (Save 20 or 30 lbs).
5. Look at purging what we carry (including tools) to the essential and using lighter alternatives.
4. Other thoughts - that 1970s bed/table is a heavy sucker (I read lots of complaints here). I'm going to try making a new one using composites or hollow-core construction. (Maybe not much saving, except my back).
5. Total weight saved: More than 150 pounds or about a third of the average load for this size of trailer.
All these measures of course require some compromise. But we bought a light
trailer, and called her "Little Green" with the desire to be at least somewhat environmentally responsible. Don't compromise on safely. But reducing cargo weight will improve mileage, no matter what your tow vehicle.