I should mention that since many window A/Cs may not have a plug that the OP may wish to empty the A/C pan by putting down a 2X6 on the opposite side of the trailer and driving over the board. This would help slosh some of the condensate out of the pan on the outside of the trailer..
IF the OPs A/C does have a plug, PULL IT BEFORE MOVING THE TRAILER..
Should be obvious as to why one would wish to empty the condensate before towing.
But if one can't figure that out, it is so you don't accidentally slosh the condensate INSIDE the trailer.