I ran the numbers on the deal knowing that I would break even on cash flow in the first year with minimal rent increases but significant cash flow in year 6 when the 401k loan is paid off.

As a result, you might end up increasing your taxes by delaying income and accelerating deductions.Did I miss something?

Bond fund holders are making a strong return with both high yields and fund values increasing with rates declining. 

I do understand that market value becomes what has been paid for a deal but with minimal work and renovations my deals almost always significantly increase in value in the first 6 months.

Great tenant but property tax increases have reduced my cash flow.

Most midwest markets offer this type of inventory.I am also beginning to talk to CPAs and attorneys, but I am not sure what questions I should have cleared at a minimum to confidently take the big step. - First, I recommend speaking with a lender to find out if you can purchase the property in the name of an LLC.

Investors focus on adding Accessory Dwelling Units (ADUs) to increase income streams.

Alternatively, can you use either unit as an STR to increase cash flow even further?

This would help everyone feel confident that your reviews come from genuine firsthand experience rather than potentially biased marketing. 

Finding which of those strategies works best for you, your goals and interests could help you speed up your investment journey while gaining experience, confidence and eventually expertise in your chosen area.