I've had a bunch of Subaru's since 1981 and I had a GMC motorhome. I built a towbar at the time to use my Subaru as a 'dingy' (I used the tow eyes as attachment points for the tow bar). (I've still got the towbar and have used it for various 'emergencies' since with other Subaru's.) However, this was my '85 RX Turbo Sedan which had the 'on demand' 4WD w/ a 5-sp manual transmission. (My '87 RX had the full-time AWD). Worked great as a towable on a trip to CO one year (especially once when we ran out of gas in the MH!).

At the time, Subaru did not advocate towing at all, but they relaxed their stance in later years. I haven't followed since they went exclusively AWD.

There are some tricks you can employ to reliably tow AT vehicles- which should be applicable for AWD, too. One common practice is for a small hydraulic pump to be installed that assures transmission fluid gets circulated while towing to keep things cool and lubricated.

-Mark