I know this goes against the conventional wisdom on this site, but I think you may be right in the sweet spot. If your fan comes on briefly each time you know that you are getting maximum cooling drag reduction. If the fan never comes on, you don't know if you are at optimum - you may be accepting additional cooling drag unnecesarily and you have no way of knowing. Yes, you are going to lose a little bit of power with the fan, but you know you are right on the edge of optimum performance. Just make sure the vehicle doesn't overheat at any time. So, bottom line is I'd leave it the way it is. JMHO.
