My 2 cents worth
I tow my Mazda Rx3 race car with my Stagea all the time ( 1999 RS4S Manual). I specifically brought the stagea to do the job becasue of the following:
Towing capablity, easly tow's down to the Phillip Island every couple of months for race meeting from melbourne. Fulling loaded with race car, spare wheels, tools, race gear, jerry cans etc...
Station wagon so i can load it up with all sort of stuff when needed.
Great for family car when dropping kids of to school ( kids love the sun roof in the back).
Go's well when you boot it and you can easly just cruise along as well.
Looks better than a Commodore or Falcon anyday for a tow car !!!
PS: And yes i tow in 5th gear easly doing 110k's per/hr off boost and still get resonable towing ltr/ per klms but you have to realistic here and not expect to get 15ltr per/km when pulling 1.5 tonne on the back. When i want to overtake i pull out sink the boot .... she come's on boost and away we go easliy overtakes.
The Stagea is stable driving with the load but it still comes down to common sense when you load trailer on the back. You have to balance the weight on the trailer and not have it over hanging and wieghing down the back of the car. ( Again this is common sense no matter what car you are towing with when pulling large loads) !!!
See you at the island