I found the perfect solution for the Catalina 2500.
I simply dropped a length of PVC pipe into the gap from above and sealed it from above with silicone caulk. It is invisible and forms an excellent gutter which seals the
awning.
Some iteration of this method would work well with your
awning which has a larger gap. Perhaps a larger pipe or even a modified PVC gutter would do well and offer a good and permanent solution.