As already said about the car backing down out of the trailer, if it has a dove tail like mine I have to push it maybe 1 or 2ft. to get it rolling down onto the door when the trailer is level
I do use a electric tongue jack and I usually unhook the trailer as most of the races I go to are two days so the trailer is raised up in the front some to start with usually
. My trailer is a 24ft. Pace and the car is a 1971 Duster, I load the car so the rear of the car is in barely enough(six to 10 inches to the rear bumper) to clear the rear door, which leaves a lot of romm in front of the car
It also places the center of the car over both axles, making the trailer pull really great