I used joint compound to cover the seams between the Masonite skyboards, as well as cover up the screw holes.
Next up were several coats of white primer to hide the dark color of the Masonite.
In the corner I tried the idea of curve a piece of Masonite. I had installed the two flat pieces first, so that I could use them to force the corner piece in place. It came out OK, but not as perfect as I had imagined.
I installed 4-foot fluorescent light fixtures above each of the two workbenches. These each their own power cord, so that they could simply be plugged in to the wall outlet when needed.