Frank is spot-on about the extra loading if it is elevated on a stand, but I suspect the two legs you have at one end are extended with 2 members that peak like an "A" to a hinge point on the spine, not down below the spine, like Frank modeled in CAD. Hinging on the spine is much better for loading and that takes some of my worry away.
As with any mount such as this, big triangles keep the load down, but also make the structural members long and skinny. Some balance between a sturdy point of attachment, and not reaching so far that the actuator bends, is what you are looking for. Oh, yes, and the stroke of the actuator travel has to be reasonable, too. So now that I've told you everything you already know (just working it out in my own head, really), here's what I would say:
Run another tube on the ribs, parallel to the main spine, that will be the attachment for the actuator. Attach it to all the ribs it passes. Size the stroke of the actuator to get the panels to travel far enough, and position the new tube where the actuator's maximum stroke can reach, minus a bit so that it doesn't run to the limit switch prematurely.
This is something I'd do by drawing it 100 times. I'm not sure I can put it all into words!