Maybe it's not the proper way, but I always transported it like this.
I just picked up an enclosed (last week) for a deal I couldn't pass up and I think I am going to be strapping it the same way.
Enclosed trailers suck!
I used one to haul my cobra to kc and drop it off, my 5.4 f150 could barely pull it loaded or unloaded. You could almost watch the gas gauge fall and the best I could do was 60 mph. Also climbing out of the car dukes of hazard style just tears up the car.
When I went to pick up the cobra I used an open trailer. It was much easier to load the car and I was able to tow it back 75mph no problem. Just make sure you masking tape the front bumper.