I don't think the idea to photograph a person in this manner would ever occur to me.
I think for me it would have been either a composition of purely the lines and shapes and areas of different textures and brightness, or one with the person visible to all ... but actually your approach is quite intriguing!
I love the photo and the format, my second camera was a 126 Instamatic with lovely square photos, when I took up medium format a few years ago I choose 6x6 simply for the format. The challenge of composition in a square image is always fun.
The bag sitting to the right of the person (or our left) is a bit distracting because it disrupts the symmetry. But aside from that it's a great shot, with a nice approach.
I actually think the bag ADDS to the photo by disrupting the symmetry. Maybe a different prop would have done the job better, but I suspect that Tuna is all about unstaged captures.
The bag sitting to the right of the person (or our left) is a bit distracting because it disrupts the symmetry. But aside from that it's a great shot, with a nice approach.