Transom space on CC boat is usually at a premium.... the transom goes straight into the water with the OB engine mounted to it. Most runabouts have a "shelf" type transom design with a built in/bolt on swim platform design that makes folding ladders easy to use.
Most CC boats I have seen use a removable Diver type ladder to get in and out of the water. An example...
http://www.amazon.com/Garelick-EEz--...ladders+diving
Woodsy