Wife wants an SUV in a year or so. Either X3 or X5. I would love to have the X5 4.4 for towing and make my m3 a trailer queen. I am estimating that my m3+trailer would be in the low 5000lb range. I understand that the x5 can tow 6000lb. I will tow around twice a month and no longer than a 120mile round-trip. Who does this? If so, what should I watch out for (excess wear, etc). Thanks