I'm more optimistic and realistic than most of the previous posters. The tongue weight given by the manufacturer is set by the such things as the configuration of the equipment in the trailer and the distance from the hitch point to the axles. Unless you load your things in the trailer very oddly, the tongue weight percentage will remain very close to the same, loaded or unloaded. Even if the batteries and propane are not included in the dry weight which is rare these days, that weight is distributed between the axles and the tongue and not all on the tongue.
If you load 1000 pounds in the trailer (which is quite alot for one; my wife and I add less that 1000 pounds not including water), 10 percent tongue weight will put you right at 700 pounds. Adding in the other weights you listed will reduce your available payload to 270 pounds.
I don't see a problem with these numbers.