I ended up deciding on completely covering the structure with 50% shade. It gives varying amounts of sun relief to the four beds. It’ll be interesting to see what grows best in each.
The dirt patch on this side of the potato trench has been seeded with wild flower and buckwheat. Things have sprouted readily, I’m hopeful for a flowering meadow in the coming months.
I’ve been watering twice a week for four hours or more. The beds are retaining water effectively, and with the sunshade even the seeded ground appears to be retaining some moisture.