I currently own 50% of a 45 unit mobile home park in South Daytona and I have an additional 4 unit property under a cash contract.

In addition, if they have had the dog there for a long time they may be able to argue that the landlord lost the right to enforce the no pets clause.

These are all great suggestions, I would add do not overlook the power of referrals and building a network in addition to online marketing.

Additionally, I have a decent amount of flexibility at this job and experience large periods of downtime on a daily/weekly basis. 

Just an additional avenue. 

We're considering buying an investment property (single family, duplex, or small apartment building) in greater Minnesota since the cost of properties is lower than in the twin cities.

We're after a multi-family unit to purchase so we can rent the other apartments.By day, I'm an AI researcher but looking to build some additional cash flow through rentals.

Any additional suggestions, advice, guidance or even cautionary tales would be greatly appreciated.

You mentioned some small rooms, this often happens when a large addition is attached to an older smaller house. 

Using the rental property calculator, Cash on Cash ROI is -7% for the first year, and doesn't become positive till year 11, after we've had to invest an additional 46.2k to balance each month.