Your idea for the drop chart will work fine as you progress in the development.
The hard part will be the "ranging" with the mil dot. I'm tried and tried, and can't get it right. An example was a nice bull w/the a half hour of ranging. I kept coming up with 695 yards.
Got the range fired and went back to that spot, the Leica reported something like just under 400. If I were betting I'd have bet on the longer range. I took my neighbor to that spot, about 800 yds behind his house, He gueatimated "some where around" 600 yds. His Nikon agreed with my Leica.
He is an experience elk hunter and we, together, hunt yotes back there every winter, all winter. We were both amazed at how inaccurate our eyes were. An mine, even with the mil dot to help.