As you have probably have figured out. The TT dealer looks at the Towing Guide and sees that your TV can tow a certain weight. The TT he is selling you is below that weight. His job is done.
He has probably sold that type of TT to that type of TV many times with no complaints to people who are only interested in “can I tow it”.
The dealer does not know the max cargo of your TV nor does he know if you carry the family, a big dog and a few extra anvils because you like to go to anvil swap meets.;)
In my case the dealer knew I would have about 800 lbs. of tongue weight with my TT loaded. My max cargo is 1411 lbs. so I would have 600 lbs. of cargo capacity for two old folks and our dog. What the dealer did not know is I also haul a canoe and camping gear, so I am often at the max cargo limit.
As mentioned already, many people are at or slightly above their cargo limit. A trip to the CAT scales settles all guesses. Once you have the real weight figures, then you can decide if it is okay or way too much.