for trailers built in the last 10 years, the yellow sticker on the trailer lists the weight as it LEFT the factory, so ALL factory installed accy are included.
what is NOT included is anything added by the dealer.
and in MOST cases the dry weight does NOT include batteries since they are usually dealer installed. it does include the weigh of full propane tanks.
Now hitch weight is again hitch weight as it left the factory it does NOT include a few items that translate almost directly to added hitch weight
1) battery(s) figure 70 lbs each
2) propane, figure 20 or 30 lbs each accordingly.
and all the stuff YOU add to the trailer that adds tongue weight.
For an example, my outback has a claimed and actually dry tongue weight it the mid 700's, I don't recall directly, but my measurements pretty much matched the factory claim.
ACTUAL tongue weight with propane and my 4 GC batteries full fresh water and trailer loaded as we travel....... 1450 lbs!!!!