ummmmmm
You were taken for a ride, there is no way the Subaru is going to tow that
I have a 2003 Forester and it is a great car, gone through several of the kids and when my daughter is done with it it is coming back to me with about 150K care free miles. because it is an automatic I am thinking of buying a newer manual to tow behind an rv when I retire. But that is having the Subaru towed
Your asking a great little runabout to do something it isn't made for. And all your going to do is ruin the drive train in the process. there MAY be a really lite weight popup trailer around a 1000 pounds that you may tow with the Sub. But if you do the first thing I would put on would be a combo transmission and engine oil cooler (if you have an auto)
I love Subaru's, they are great cars. No way can they tow what you want