This is a really interesting find with the under specd hitches.......I am not sure what year it changed but I just built an F-150 online and you can get it with a Class IV hitch from the factory. I messed around with the Online Builder to see if it was dependent on the trim package or anything else and you can add it to any of them in fact it looked like the only hitch you can add is a Class IV. I currently have a 250 so I am not worried about it but have been considering getting back into a 150 in the future.