This was my final set of 5. Looking back at the course video, I don't know why I was thinking that the tripod was supposed to be done as a tuck rather than supported on knees. I can go back to doing them that way.
My shoulder mobility isn't great; I'm arching a little and my arms don't get back as far as I'd like. I'm not sure where the threshold is for when I can move on from this mobility element though.