The book and any stated tongue weight will vary when you are loaded.
And your set up is fine for all your intentions, but you may very well have the pedal floored going up steep grades, running high rpms, to hold a decent speed.
Gas engines need to rev to make power, and no matter what gas engine and travel trailer configuration one has, this holds true.
Typically I have found those who claim to be underpowered while pulling with decent gas engines going up steep grades are too easy on the gas pedal for fear they are hurting the engine. That is not reality.
Finally...don't use GVWR! This is simply the max the trailer can carry, and should not be what you ever end up with in reality, to constantly travel with.
Estimate what you want to add to the camper and add it to the from dry weight or better yet the "unloaded weight". Typically 500-1000lbs roughly, are good number. In my case, I typically only added 300lbs of stuff, this year I'm up to 500 with 4 bikes and a single rack. Everyone loads theirs differently.