I decided to use the fittings that are made for the conduit, to anchor the ends of the hoops for the cockpit cover. I got a couple of "+"-shaped joints and cut them in half, making 4 sockets that I could screw down onto the deck. I clamped my vise to my kitchen table:
I cut on an angle that I thought was going to match the angle of the posts.
I don't think I angled it enough, though. I thought the aftermost hoop needed to be inboard, to keep it out of the way. Outboard looks like it would interfere with the mizzen sheet fairlead.