Luxury Diesel SUV as tow vehicle

Hi, I'm looking at people who have experienced towing with a diesel SUV. I'm planning to replace my current vehicle (2009 Toyota Highlander V6 AWD) in a year or so and I'm interested by the following:

2-3 years old (with less that 60000 miles), these SUV are around 35k (in Canada)

BMW X5 xDrive35d
Mercedes-Benz ML350 Bluetec
Volkswagen Touareg TDI

These 3 SUV averages 250HP and 400+ Lb-ft of torque

I have a 18' travel trailer weighting 4600 pounds loaded for now. I'd like to get a 23' with bunks (about 6000 pounds loaded) in the future.

I do not want a bigger SUV than the ones listed (nor a pickup truck), as it won't fit in my garage!

My 270HP, 250 pound-ft of torque Toyota does the job well right now, but it would be nice to get more power and torque if I want to upgrade my travel trailer.

Thanks!