However, Total Protect Home Warranty just recently did anything and everything they could to not repair/replace my HVAC on another property, so I don't want to end up with another company that will leave me to replace it myself again.

You might consider buying a 3 bedroom 2 bath that needs rehab work that sells for about $25k and another $30K in rehab work for an all in cost of $55K with a possible and likely rent of $1,200.00 per month After repairs.

For example, I just analyzed a park that had an actual expense of $8,400 for septic repairs/maintenance. 

For example if I by a duplex for 100,000 the gross rents should be at least 1,000 that is after all repairs etc.

if you need to supplement the costs further you can consider renting rooms out in the unit that you live in but this typically is only an option for those who need the financial assistance (housemates are often not easy).You learn Property Management, if you like being a landlord, doing repairs and hiring contractors. 

He’s very good at thinking outside the box and has saved me tons on repairs/replacements.

I think it is a red flag that she wants to rent your place 3 months ahead of time, unless you are in a very hot market. 

The standard calculations are usually 7% - vacancy, 10% - repairs, 10% CapEx, 10% - still for management.

Regardless of the cost from the refi, it's still a cost, and he will have lost the opportunity to move ahead by investing it. 

I should also note that these are turn key and require no repairs.