I asked about pop -ups as those can be really light for old subarus,...like 1000lbs.
based on your Utah IP,...you are dealing with very tough towing conditions for any subaru, and particularly one such as yours,
(20 year old H4, high altitude, big long grades, ...high temps possible.)
what cars pulled this thing before?,...If its almost Free, and the owner tows it over to you on a HOT day with a 160hp/ 160torque car ....maybe.
and the possible worst thing that can happen,...you blow the radiator, or loose the brakes, and sell the trailer to someone else.
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worse than that: this pic has been posted here before
going up hill a heavy trailer boils the coolant and transmission fluid, going down it cooks the brakes.
the driver in this pickup, is still in it, and is probably happy they crossed the safety chains, ...as those are the only things holding the truck on the mountain....and the overly heavy boat is acting like a nice anchor. (I am thinking that is something like a 1990-99 Chevy 1500 or 2500 2wd there, without enough brakes on the truck or trailer to stop the boat from shoving it down the mountain,...I am thinking the pic is from a cop helicopter,...earliest use of that pic I see on the internet is a Feb 1, 2001 ???)