Correct, GVWR= how much the trailer can hold, including the weight of the trailer. There is also a 'dry weight' which is how much that trailer weighed when it left the factory. This includes factory installed accessories, but usually does not include battery or propane weight as those are added at the dealership. Somewhere between your GVWR and your dry weight is where you'll probably end up. The difference between those two numbers can be considered your Cargo Carrying Capacity, or CCC. Your Subaru also has a GVWR which is the total amount of weight your can have in your car, including the car itself, passengers, fuel, and gear. The tongue weight of your trailer will also eat into your vehicles GVWR and your vehicles Cargo Carrying Capacity, if there is a published rating for that.