You have an interesting question. In researching pig cookers on the internet, there are many varieties that are considered to be “pig cooker trailers” that are cookers mounted on trailers for the purpose of taking the cooker somewhere in order to grill your pig. Sine the policy doesn't define trailer, standard practice is to go to the dictionary. Merriam Webster Online defines trailer as a nonautomotive vehicle designed to be hauled by road, as a vehicle for transporting something (a boat trailer). Based on this the pig cooker is the same thing; it's a trailer transporting the pig cooker, and chances are it's also carrying the pig and wood chips/charcoal inside it while being transported. Apparently pigs are better the longer they are cooked, and they may be cooked from 5 to 27 hours. Therefore, the pig's probably in the cooker being roasted on the way. We say the roaster is a trailer, and bon appetit!