What would you consider a good minimum profit margin?

I would also urge you to make sure you fully understand how they operate , A-Z (from how they make their profit to how many doors they are managing). 

A professional property manager should handle the heavy lifting, ensuring your investment is protected and profitable without adding stress to your plate.

Tourism (LTR transitioning to STR) and lack of housing  make it a very strong market if you don't mind a niche. 

A good place to start figuring out profit/cash flow is to search the forums for the 4 Square Analysis. 

To scale this route you need to have a good system in place to ensure you are profitable.

Also, the whole point of hiring a PM is to handle tenant, maintenance, and rent collection, so if your partner isn’t actively managing but just supervising the PM, IMO not worth having a two people essentially looking over the same tasks.Contributing financially for one person and the other having no financial stake raises decision making questions, such as when to sell, how profits will be distributed, etc.

The real estate market has shifted dramatically in recent years rising interest rates, evolving buyer and seller expectations, and fluctuating property values are keeping all of us on our toes. For fix-and-flip pros, ...

I own 9 rentals in SC spread across Columbia, Chapin, and Newberry that are solidly profitable. 

Happy profits!!