Perhaps if your partner was a general contractor or handyman type there may be some merit there to reduce costs / increase profitability.If your partner enjoys deal sourcing, a better move might be for him to become an agent - so he could legally collect commissions from finding deals and managing properties for multiple people. 

While the vetting of residents is greater with FF over an Airbnb or similar platform, I think Airbnb overcharges for the increased convenience. 

If you have access to some money you can increase your equity in one jump.

This is where your focus should be, not buying section 8 rentals or focusing solely on increasing your portfolio by 2x, 3x etc.

Currently we are seeing STR owners posting for sale due to reduction in prices they can get per night and the vacancy rate increasing. 

Borrower has the 3% loan in place for the duration, and 14% investor can be paid off with increased rent in say 18 months.  

I'll admit upfront that I would never own rental property in CA, so that colors my response.I'd offer the tenant up to $10K to leave immediately, keeping the eviction off their record, then sell.

It's tempting early on to leverage as much as you can so you can do more deals and keep liquidity, but increased cashflow especially with PMI will make you sleep a lot better at night.

Or is it calculated daily and the base rent increases after 10 days when the late fee hits the account?

The increased risk is generated by the fact that the owners are relying on the validity of the tenancy in common Agreement for their usage rights, and it is possible to imagine legal circumstances under which this validity might be undermined.- If the subdivider or someone with relationship to subdivider sells, a public report must be done.