On the Riviera, the motor stringers extend to the transom. My brackets are bolted thru the transom into the ends of the motor stringers. You will need some form of support structure but it does not have to be excessively large.
My exhaust trumpets are in the bootstripe. My swim platform sits directly above the trumpets with only a 1/4" clearance. I am having no issues with exhaust, drag or anything.
I really like the merging of the swimplatform with the spray rail . There is an inherent technical issue that needs to be addressed though. The juncture of the platform to the spray rail will have a degree of torque which implies stress points where finish or joints will crack. I suggest that this joint be a type that allows movement.
On the Tahoe, I really (and I mean really ) like the integrated platform. There are several Van Dam boats that use a reverse transom with integrated platform. They have the room to build steps into the transom as well. We see this on a number of Riva boats also. (Zane- it is not too late

). To me this is a really nice setup and one I hope to achieve if and when the Admiral lets me build the next ride.
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Dave
My Riviera build -
the Midnight Cry Project Video of Midnight in ActionBlogFew things in the world measure up to the thrill and satisfaction of boating in a boat that you built.