A super ball number to get you going would be at least $190/SF-$220/sf ish... to figure out square footage it's probably best to connect with a Chicago architect like @Samuel Pavlovcik or @Prashanth Mahakali both can talk through the zoning and plan development process.

Also, you're able to keep the loan current if you're planning to keep the seller's name on the mortgage until it's paid off.

I plan on building a duplex (so 2 kitchens and 2 living rooms).

(I hopeful that you planned for this in advance.)

Lenders who understand and specialize in such properties can be more flexible with their criteria.One approach is to ensure you provide comprehensive documentation on the property's potential and zoning specifics.

You can plan for it, but it's going to be slow.

Easy to write a state specific lease and make tweaks, and send for electronic signature.

This is 100% top advice to think about - each state (and sometimes, often municipality/city) will have different processes, rules and yields for this - it is a very location-specific strategy and have to hyper-focus on a local market (more even for the rules/process than the real estate knowledge) to have success

my goal is always to have passive income from rental properties but right now I’m thinking more of being able to pocket cash and later make plans on rentals.

On top of the fact that I already have a business plan showing that income from the other ag operations cover the annual payments?