Hi Martin,
It’s not an SE but I recently had some luck making an engine bracket for a 21sc. It was inspired by the commercially made Cheata Bracket but utilizes a single piece of aluminum that cups the rear crossbar. Instead of rivets the bracket is attached to the rear bar with three 1/4” bolts that run completely through the crossbar and into the front side of the bracket. I also applied automotive style “window weld” between the crossbar and bracket to eliminate any saltwater festering between the two pieces of aluminum.
Some aspects of the bracket are way over built and could use refining but I feel much more confident leaving my engine on the back while trailering.
I run a Suzuki DF2.5 which worked well with these hills. At 30lbs the engine is easily pulled up and placed in its upper position for sailing.
Here’s my attempt to post pictures. If anyone wants more details let me know.
https://photos.app.goo.gl/PXq7ZBYbK3gadkeZ9