What is the best point to jack up a Cobra Trailer ?

After reading Steve's response, I have to say that he is right and I was wrong. However, I do suggest that the jack should be placed under one of the crossmembers behind the fender, as Cobra often has the axle positioned slightly forward of the actual mid-point of the trailer box. On my (old) Cobra, the position is quite a bit forward of the middle. If there are no crossmembers on the newer Cobra models, I would suggest using a 12 inch 2x4 between the jack and the trailer body to spread the load somewhat. And don't forget to loosen the lug nuts before jacking the wheel off the ground.