There are still a few pocket areas of the Oregon Coast that do not have any restrictions, many where active rental permits transfer to the new owners, several where the allocated number of permits has not been reached or where there are very reasonable waitlists for a new permit (often in the single digits.) 

you should focus on getting a real estate CPA.As for the bookkeeping - make sure you have someone that focuses on real estate so at least that person can allocate the differences and not make a total mess for the CPA at year-end.

The fact that you do not have the reserves to handle this after 10 years is a clear indicator that your allocation to maintenance/cap ex is insufficient.  

Would definitely want a strong private agreement but all parties could remain on title with allocations.

Just because they don't have their own equipment right now doesn't mean they aren't successful but may just mean they need more time to allocate the correct funds 

I am seeking a property management tool to schedule showings, screen tenants, collect rent, and allocate maintenance requests to one centralized platform.

It might be worth consulting with a local real estate expert in each area to get more nuanced insights.Given your budget, you could potentially diversify by allocating a portion to each location.

It cost money to own a house and people normally allocate a percentage of the revenue towards repair, capex, vacancy and property management.

It is my opinion that if you find SFH that breaks even as an LTR after properly allocating for all expenses in Dallas/ft worth area you have done well. 

Note it will take time even if/when sufficient money is allocated.