They would cash his checks (even huge ones like $20k) for a small fee, and he would take the cash and pay his guys.

My lease has a sublet fee (2 weeks is guest by lease more than 2 weeks in a year is sublet) that is costly enough ($100/night per person which is about what a cheaper hotel is here) that makes sure tenants do not have others move-in without informing us.

Second, as sponsor you want a 1 - 2% annualized return asset management fee AND 20% of the profits after the investors get their money back.  

There ae also holding costs, After the flip you have real estate fees and closing costs to pay.

I hope to use private capital to fund the entry fees in second position.  

Most turnkey companies proforma does not tell the complete story and that is why is called "PROFORMA" OR "PROJECTION", they don't account for the true vacancy, leasing fees, holding costs, and Headache factors that come with a Class C and D properties and neighborhoods.Hopefully, they can help you get to 100% occupancy and sell the property so that you can re-invest in a better neighborhood and relatively newer property like 2020 or newer if is possible in that market, or just go to another market you understand better or have some kind of connection with.All the best and keep us posted on your progress.

How much is reasonable for management, accounting, and rental commission fees?

Quote from @Juan Ruben Cortez: I believe the funding fee is 0.5% of the remaining loan balance, plus maybe another $500 - $1,000 in lender fees. 

You will have to gather more accurate operating costs (vacancy loss, taxes, utilities, insurance, mgmt fees, maintenance, HOA) to best determine potential future performance.

I used Hostaway for the last year and the they recently snuck in a 1.8% fee for our direct booking site.