2003 UK Outback (yes, diesel powertrain, but the diesel is actually rated 100 kgs lower in towing capacity on the 2010 website, so we can logically presume that the gas versions of the same chassis for 2003 were AT LEAST equivalent to this).
Max Towing (with trailer brakes) - 3748 lbs. (1700 kgs) - (without trailer brakes) - 2551 lbs. (1157 kgs)
and this PDF for 2004 UK Outback agrees -
2.5L - Tow Capacity - 3968 lbs. (1800 kgs)
H6 - Tow Capacity - 4409 lbs. (2000 kgs)
Now what this means to an individual in the US from a liability standpoint well, that's up to you to decide.
BUT I think it is strong empirical evidence that the chassis can handle more than the artificially low limits that Subaru publishes in the US.