Greensand sounds like a good bet.
IMHO on sand, irrigation should be more frequent and lighter; a tenth of an inch per day would work; add 25 percent if temps rises above 85. Corn gluten meal and alfalfa meal are fine, just remember they are low in nitrogen--it will take a lot to get dark green color.
Maybe Barry at Phasthound can advise you on the best fert for your sandy situation--and yet help you avoid contamination of lake Ontario. Over time you can build up the organic matter in the soil. The roots will provide more stability. It won't wash away during rain or blow away during storms.