Temps haven't been real hot here yet so that is a factor. Additionally I haven't towed anything super heavy yet. As such, I just don't anticipate it being a problem. There is still a good amount of room for air to flow around the hitch. There is a decent amount of clearance between the hitch and the coolers as well. I would think that the aftermarket winch bumpers or even some of the grill guards I have seen would be just as restrictive.
Again, I just can't see it being a problem. I will be helping my father-in-law moving his swather, bailer and tractors later this summer so I will be giving it a good workout then. If I do notice anything I will be sure to post it up.