Did I "have to"...No! Did I? Yes! Mini has loads of power (160 hp w. supercharger) and is actually quite heavy for its size. Trailer (alloy) and boat weigh in at under ~900 lbs. Pulls quite easily on the freeway and even up the big grades we have around here. I used to pul a steel tilt trailer with a VW Rabbit...that was more challenging...less power, lighter car and softer suspension.
I no longer use the mini for longer trips (>100 miles) as I have a Eurovan pop-top weekender for regattas...no more stanky motels.