Good morning Josey:
You are right about the sun. Plant physiologist say that most plants only thrive up to temperatures of about 25oC. This means in full summer, anywhere you get 6 hours of sun a day, you probably need some shade cloth. When we think about it, so many plants evolved and adapted under filtered light. In fact once you become shade'/light conscious plants are easier to place. You can think of leaf canopies as being 50% shade, 70% and then with big old conifers, 100% shade. I think most plants like about 50%.
About plant placement, as you know we think how will this plant/s function in this place. There's often a conflict and so at my place I need very badly a good thick windbreak to the west, and I also need
solar gain for passive
solar in the house. so it is a careful balance to get the thickness, height, and filtered light. I spend many hours thinking about it. It is fundamentally windbreak design but I don't want a giant hedge. You can see how often there is a tension in placement of plants and not only because of the plants requirements but also your design.
The questions are never fully solved. So you get closer to the solutions you need. Another for me, is that I don't want to make future work. I don't want to be stuck with hedge pruning every year for the rest of my life.
You are obviously thinking permaculturally and will do a lovely design job.
warmly
Rosemary