I would send a letter to all units of the building reminding them of the clause in the lease you cited and let it play out from there.

For our next play we want to get into a single or multi-family, and preferably participate in what seems like a booming market in Florida. 

@Justin Jefferson first, some cold realty - you're about as likely to play in the NFL as you are to retire via real estate in 4 years.Are they both possible?

Amortization length along with any DSCR requirements comes into play also to determine what kind of down payment requirement you may have to meet. 

You can only play games for so long.Chances are your next door neighbor is an IRS agent and turns you in when your tenants blocks their drive or some other random event disturbing your IRS neighbor.ADU catches fire and your insurance won't cover you, because it was an illegal and unpermitted structure.The city inspector told the last guy not to build or rent it, and is now pissed and wants to make an example of you and just red tags the whole property and no one can occupy for the next 1-2-3 years while you wait for a hearing.Then when you get the hearing, "staff" recommends you tear the whole structure down, and if you still want an ADU, you can apply for a permit and rebuild it.Your tenant quits paying rent and won't move out and you can't evict them, because there is no valid lease and they're just your "roommate".Probably a dozen other bad things can happen to you when you do stuff like this. 

Basically every personal house we ever owned except this last one which we built from scratch.

You’ll learn way more hands on than spending money and another 6 months being led on by someone who is playing you.

I'm still playing with the layout and trade-offs.

Hence you can see how interest rates play a large role in determining cap rates in a market in my opinion. 

Detroit is literally one of the, if not THE, best markets you could be playing in today.