I want to thank you all for the great information and advice. I've learned so much from this website.
The owner of the remaining 3 lots, Fleetwood Homes, finally got back to me and unfortunately they already have plans to put new homes, not duplexes on those lots. Bummed me out. He said if I would have contacted him last summer he would have worked with me on the one lot that is next to other duplexes. They break ground in the spring on the 3 homes.
@Karen Margrave yeah Fleetwood Homes owned all the lots/land in that subdivision and these were the remaining 3.
@Andy Mirza the area these lots are in are in the school district we want to be in. It's a small town, Carlisle, Iowa just outside of Des Moines. This subdivision is just off of a nice lake Easter Lake and the city is doing many upgrades to the area. just a very pleasant place to be. The current duplexes that are there are really nice. They aren't townhomes. They rent for $1500+ and most are rented by people in their 50s and up. I'm guessing the home owners in the area don't mind as these duplexes really look upscale.