I have an 8+ x 20 ft. enclosed trailer for my Diablo. (They aren't really 8.5 wide, closer to 8'-3" and less inside)
Because the Diablo is so wide, I made ramps to keep the sides clear of the inner wheel housings AND to make it easier to attach the tie-down straps. Remember these cars are VERY low and if they sat on the floor, it would be hard to hook them underneath.
Check out these pictures:
By the way, the tape strips you see on the door/ramp help align the car to center by representing the outside of the rear wheels. So when I load the car, I just keep the rear wheels aligned to the tapes and winch it in. Also, load Lambo backwards because you need tongue weight for the trailer to tow correctly. The engine in back is your heavy end just like the engine up front is the heavy end of a front engine car.