Towing wise I have used an old 4.0 cherokee sport (the smaller jeep, but was still rated for 3500kg towing) on LPG. With the auto and cruise control it was a dream, and running on gas not excessively expensive, hills no problem, and even on road tyres I rarely had to put it into 4x4, never mind low, although mine did have the LSD at the rear to help. The other option is almost any green oval product.
Jap stuff, especially imported autos I would be avoiding, the imports are not used to heavy work normally, so long hard drives, steep hills and big trailers can cause failures.
Please be aware that at these kind of weights, the car may not be your biggest problem, she will need +E on her licence as you will be well over 3500kg train weight, which if she only first passed after 1996 is a separate test.