Hugo, thanks for telling me about the spots. Not sure how that happened - I must have loaded an intermediate file. I have updated the photo with the correct version. I hope it is a bit better. I'm not sure about a vertical canvas. It makes the whole thing very centered. I'll have a look at it again and re-evaluate it.
IMO key thing with silhouette images is keeping the subject parallel to sensor frame. Since there is no detail in the subject, the outline of the subject is what makes silhouette images interesting.
Like the colors and interesting tree.