The Subaru models I have experience with were tow rated for up to 3500 lbs. with the appropriate hitch. But I would not tow a trailer that I could not stop in a reasonable amount of time and distance using the tow vehicles brakes alone.
Before I bought a travel trailer I would get the hitch installed and rent a Uhaul trailer and load it up with as much weight as possible and then see how the tow vehicle performed. How well it was able to accelerate and safely merge with traffic, how well it was able to go up a 6% grade, how safe it felt going down a 6% grade, and how long it took to bring it from 60 MPH to a complete stop.
None of these factors are given serious consideration by any of the car manufacturers. My Chevy Tahoe was rated for double the load that it could bring to a stop in less than a 300 feet from 60 MPH. With its rated load in tow it was not safe to drive.