So I am declaring my lettuce in crates a success. Right now we have more salad than we can eat and is mild enough for my picky taste buds. Growing greens in potting soil definitely makes a huge improvement on the taste, plus I can move the crates farther into the shade as the spring progresses.
I planted a total of three wood crates and three smaller pails with lettuce and some spinach as well. Next year I would like to get them planted earlier, but I am happy I finally found a good way to grow my own greens.