We recommend dividing your unit up into 3rds and do a light disking on a 3rd every fall between Aug.15 and Sept. 15. On year 4, you should be starting over on the original 3rd you disked the first year. You can use these areas to put out millet if you want. As far as how to hunt it this year, I would do just as you suggested. Knock down a couple holes in the middle and hunt those holes early when you have less water. As the season progresses and you add more water, the ducks will probably try to start landing outside of the vegetation in the open water. At that point just be where the ducks want to be. As you stated it's only about 90 yds wide, so conceivably you should be able to set up right in the middle and reach both edges.
All depends on how long its going to take us to do a job. You can borrow that spray rig anytime, just let me know. I've got a job up towards Tippo that I've got to check once a week if you want me to bring it up.