I have an 11 ft. Boston Whaler with a 15 hp outboard behind the flybridge on my 1965 50MY. No stability problems. Fanfare heels over about 18 " when launching the dink due to the weight and leverage to port, plus me and the Admiral tending the lines on that side. (Make sure dinghy's bow is facing forward when launched when constructing cradle. Backwards was a mistake!) It would be convenient to be able to launch to either side, but I couldn't figure how to do it. An electric winch is almost a must.
Many years ago I found a problem with cracks in the fiberglass of the flybridge deck at the top of the side mahogany uprights. I think this was due to stress of carrying the tender, which was smaller at that time. I added a 2" steel tubing upright in the center of the afterdeck to strengthen the structure, as the bridge deck was unsuported behind the cabin house. My theory was that the stress was caused by the dingy "hobbyhorsing" in strong head seas. This probably would have solved the problem. However, later on I replaced the davit with a stronger one. It is on the port side, and runs down through the bridge deck to the main deck to spread the load. Later still I built a matching radar mast to stbd. Both of these tie into and support the bridge deck. I removed the diagonal bracing Hatteras had put in as this was now superfluous. I have had no more problems.
Hoisting the tender up on top is sometimes a pain, but once it is up there I know it is safe from theft. So many dinks and engines are stolen today. I spend a lot of time in the open sea, and would worry about the effect of breaking seas on a swim platform mount with the buoyancy of a tender being that low. Since I don't have a swim platform that's not a problem.
Sometimes I consider an inflatable, but they are so much larger. I bought this 11' Whaler new in 1975 and it is still good as new today. It's great for three adults, but you will want to check the size of the waves if you are taking four very far.
