I talked to the owner of the Tanzer 10.5 with the swim platform. He used a shower wall liner strapped to the hull to get the outside shape. He waxed it then laid the glass in it. He then removed it, finished the layup with plywood for the inner walls trimmed and bonded it onto the transom. It looks like there are also a few bolts through the transom.
The exhaust is routed out the port side and you can see the fittings for the dinghy davits. The dinghy gets stored resting on its gunwale.
You can see the integrated rudder stops. There are lockers molded in, the propane tank is in the starboard side locker. The handle on the rudder is in the perfect place to grab when boarding as I found out going aboard.
Oh, and he has some wooden boards that fit around the rudder when not underway to make the platform easier to navigate; that's why there are fiddles around the inside of the rudder opening.