It's been a number of years since I looked at the Outback specs, but I believe the Outback is rated to something like 2700 pounds towing with the 4 cylinder engine. Consult your owners manual for the actual numbers. As far a the 1 1/4 inch receiver size, Subaru would have kept tow ratings in mind when designing the hitch receiver, if it is a Subaru factory hitch. Additionally, the rated tongue weight for the Outback is 270 pound. The owners manual for my 2013 560 states to keep the tongue weight between 140 and 220 pounds. Just pack the camper to correctly balance the tongue weight between 140 and 220 pounds and you should be more than safe. Again refer to you Outback owners guide for actual ratings (I got mine of the web).
I also highly recommend to get electric brakes. You should consult for regulations for the state you live in concerning electric brake requirements in relation to trailer weight. (Besides, I just think electric brakes are a good safety feature to have, but that's just me).
Overall, I think the Outback is a great choice in a tow vehicle.