My 2.2 manual SE Nav tows a 1500kg Bailey Unicorn easily. Before I bought the car I concluded that it should tow 1800kg legally and safely.
However, beware that caravan manufacturers understate the true weight of their units and the plated weight is misleading. They seem to ignore that caravanners also carry a battery, gas bottles, a motor mover, crockery and cutlery, bedding, toilet fluid, etc., etc. and when you take this lot into account there is a **** of a difference. I discovered this at my last 'van service when the dealer weighed the 'van and said it was overloaded - even though I had emptied the unit of personal effects. A tyre had also been rubbing one of the wheelarch liners - which was a shock. As an aside, there was a manufacturer's label in the gas compartment stating a weight greater than that stamped on the plate so that is what I work to. Also, I now load the car rather than the caravan. The more I researched this subject, the worse it got and the more angry I became; it's a can of worms to keep the sales figures up. Double-edged because modern cars are becoming lighter and the engines smaller whilst caravans are having more and more luxuries installed (e.g. aircon units, satellite dishes, microwave cookers, additional shock absorbers, etc.).
Be prepared to ask some awkward questions on this before you part with your dosh and form your own opinion on the responses.
A double axle shouldn't be a problem as long as it is within 1800kg. Incidentally, the firm that supplied and fitted the towbar told me that not any old towbar will do, it has to be matched to suit the weight of what you intend to tow. As a warning to others, be aware that not all wiring kits for towbars carry a supply for the fridge or for charging. This isn't just the Antara, my pal's new BMW suffered the same omission when his was installed.
The Antara AWD is the best towcar I have had over 35 years of 2 litre turbo and 2.5 litre Peugeot diesels towing ancient and modern caravans. That's why I intend to keep it for as long as economically possible.
2015 2.2 CDTi SENav 163ps manual 4x4 in Carbon Flash with 19\" alloy spare towing a Bailey Unicorn III Madrid @ 1500kg.