I would have to see a close up of the damaged area, but I agree the angle is wrong unless the trailer was going over a snow mound at the time of impact. A photo of the area beside the truck would help as well. I can see there not being tire tracks right beside the truck if the truck pulling the trailer was making a hard left turn, the passenger rear corner of the trailer would swing really wide. Just watch some people with four place enclosed trailers at gas stations. Those posts get hit a lot. If the corner of the trailer did hit, I doubt the driver even felt it. The damage is pretty light. Need more and better pics to decipher the event.