It isn't the pulling that you have to be concerned with, it is the stopping. If you are going to be on flat ground, there should be no problem if the load is light. If you start to traverse a incline or sloped ground, it can become problematic quickly with a heavy load. Even if the tractor wheels stop turning, the weight of the trailer might just be enough to push the tractor even thought the wheels are stopped. If the trailer were to start going sideways, there is no way that you could control it. I have seen trucks pulling trailers that were pushed through intersections because the trailer over powered the truck. That is why brakes are required on trailers over a certain weight/size. Make more trips, but you are going to be safer in the end.