If I commit to this path, my goal is to generate a net income of $300,000 per year by December 2030.

Tons of returns set this system off: errors, no income lots of expenses, disproportionate expenses, etc.When all that is done, IRS has a budget for how many returns they will put in the audit queue.

My idea is to put 20% down on a $1 million property, with the remaining $800,000 paid off over 8–10 years, depending on how much yearly income the seller would want.I’ve seen a lot of discussions about using seller financing for investment properties, but not much when it comes to primary residences.

May not be your cup of tea but they are cost efficient and they work to add passive income at a fraction of the cost to build a SFH.There are a few "Tiny Home" builders in Tampa and Manatee doing a ton of business.  

More on DSCR loans: DSCR loans won't use your income to underwrite the loan. 

Lender does not look at your income, just your FICO and they want to see rental income.

@Yael DoronIf you're working with a $150,000 budget and aiming for high ROI through rental income, consider nearby areas around Phoenix that still offer affordability and growth potential.

Appreciation is a real thing and not only this the demand for quality low-income housing is real. 

Start to evaluate deals based on the income approach and you'll do much better long term investing. 

They are able to rent property that is lower income housing, because otherwise the property would be vacant, or better housing where the landlord hasn’t completed a thorough due diligence either because the landlord left the due diligence to the leasing broker, or doesn’t know how to go beyond a $15 “tenant report”. or the property is sitting vacant and the landlord decides to “take a chance”.