Back to this (edit ^ yep ^ but more screws up top.)
Screw and glue (epoxy or urethane)
Use a bunch of 3" $10 SS decking screws going in perpendicular to the hinge mount screws (don't let them interfere.)
Then move the hinge back up top. But get bigger hinges. Some that allow the hinge screws to be further back on the post.