So, time to get creative!
What would happen if you went to HD, Lowes, or your favorite hardware store and bought a length of heavy alum. angle (say 1/4"x2"?), and use that to fashion a couple of brackets?
There's a very sturdy looking stern eye that's just screaming to use it to hold the back of the top section level with the deck. From there it could also be used to support hold the section leading down to the water out away from the boat.
The rear most M bracket that supports the deck could have a couple pieces neatly bolted to it to help you out as well.
Think it through, do a neat job, and it should look fine when done.
Oh, and one of those 4-6" angle grinders cut through alum. like it's butter. If you don't already have one, a job like this could cover the 20 bucks or so they cost at Harbor Freight pretty easily....