I'd get a task rabbit or your PM to take a picture outside every month to help ensure the yard is maintained...watered, weeded, cut.   

Additionally, flood insurance is commonly available and ensures that for an extra few hundred bucks a year, you're covered both for damage and loss of use (i.e. missed rents). 

Get some help to ensure you don't lose your money.

Ideally, create a separate gate to be used just by the ADU tenant to access their unit.Natural light: ADUs are small and one of the best ways to make these spaces feel bigger is to ensure lots of natural light is flowing into the unit.

If you are seasoned from a lot of flips you have the means (contractors, knowledge) to deal with about everything efficiently and deep enough pockets that you can afford to loose money on one deal. 

Have gotten estimates $11,000 to replace with a gas high efficiency boiler.

I'm now replacing two high-efficiency condensing gas boilers that have corroded. 

I obviously dont know each state, but the only person Ive heard mention on BP that it was legal in their state was a Florida agent.I'm fairly confident that it's technically legal in Ohio but my understanding is the Division will scrutinize the heck out of you and require a ridiculous amount of disclosures to ensure you make it clear to the seller that you are going to make a whole bunch of money off of them.Like you literally need to have them sign a document that says something to the effect of my commission will be anything I can sell your house for over $100k.

Use the BP calculators to ensure you have enough cash flow if you rent it out!

Ensure you have a small emergency fund to cover any unexpected expenses, then set a budget for yourself and put as much as you can away to the credit cards.In the meantime, you should start educating yourself on real estate and practice analyzing deals.