Now, wait a minute. Is your boat on a trailer or is it on a cradle? Cuz you refer to "the trailer" in your original post and you also say that a guy will launch it from a trailer "off the cradle from his trailer". Which begs the question of how he's going to get your boat from it's trailer to a cradle.
If it's on a cradle, the poster who suggested a swing keel boat on a trailer may be a wise man. He made the point of what happens if you need to haul the boat for an emergency. That's a very real consideration. What happens if you decide to do extensive work on the boat one Spring, like Awlgripping the decks...and you miss the date for the crane?