I found a property for a fix and flip that turned into an opportunity to buy 4 pieces of property (including two abandoned homes) attached to about 100 acres of land. Preliminary research shows that it might be a good opportunity for a sub-division land developer, so I am trying to get the land tied up with an option agreement. I am getting a handle on what to offer for the land, but Here's the question: What do I offer for the option agreement itself, on such a large deal.
This is one of those questions without a specific rule of thumb. The shortest answer is "as little as possible." For rent to own SFH typical is 3-5 %, which is about what the tenant would need for an FHA loan. It sounds like you need a local mentor to talk you through this. Find your local REIA, if you haven't already and see who does land purchases.
Or consider treating it like a wholesale deal. Good luck!