The monthly fee for renters ins I thought should be optional as renters insurance is so cheap and I already provide hvac filters. 

Meanwhile, explore options with other STR PMs. 

Unless maybe you have an option on the purchase of the real estate or something.

Gas or electric would be a much better option, safety wise, from a house fire standpoint, CO danger, or danger to children or pets from the open flames. 

Yes, use of single office space did die off with COVID, but because there was not an option. 

From time to time, I will see brokers list in the private remarks - "The property can't close until X date unless the buyer wants to pay for early issue title insurance. " This may be an option for you but TIME IS MONEY and why lose potential buyers or offers by creating roadblocks to your flip project.

Since you're putting 15%-20% down, a conventional investment loan will likely be your best option.

You won’t find many seller-financing deals here, so if you're looking to scale quickly, your next best option is the BRRRR method—using cash or hard money to acquire properties and DSCR loans to refinance into. 

Willing to exhaust all options as this is a big fish. 

But I would remain open to long-term rental as an option as this seems like a more stable option in terms of income, again this may be my inexperience talking.However, I have always  been somewhat risk averse and investing in real estate is always a big venture, in my opinion/experience, in terms of capital.