Another option is to make a little jig that you slip in to hold them open while you install them. I’ll see if I can find the one I did - it’s just a wedge that you twist, like a T-handle.
Actually - like a holddown pin, but without the slots to allow flex.
Edit - here’s the one I made (just the bitmap, I had it in a Powerpoint doc I use for sketches like this.) I scaled it in the workspace to get a size that worked the rings I was using.
