What he was trying to say is that prowler trailer you saw probably was not custom. You could order one from chrysler when you bought your prowler.
Obviously none were offered for the crossfire so you would have to custom make one yourself, which I have thought of on many occasions. Its a lot of work making one look right though. It would need to be very very light as well for easy pulling. It may be better to make one of fiberglass than to start off with the back half of a car. Just an idea anyway.