I am helping a client who is also a Veteran to do this exact thing right now; at first he wasn't sure he wanted to move twice to make it happen, but when he realized he was going to basically get a cash flowing rental property for free(no money down) he realized it was an easy decision.

I started investing as an OOS investor here back in 2021 and haven't been disappointed with my decision. 

I've checked references and visited their work on other homes but am still agonizing over this decision.

If people are getting free electricity and water, they tend to be a little less frugal :) .Then check on insurance costs for a MFH and add that to your projections.Finally, talk to your contractors and see what requires permits, what their experience has been in getting them to pass inspections, the timeline and the cost.Factor all of these into the decision to move forward or leave as is - maybe advertise it as a 4/1 with a home office with outside access and get more rent that way.One last point - I hope that the addition you mentioned was done with permits and is reflected on the tax rolls because if not, you may open a can of worms you wish you had not.

By using a F&F calculator, you can make informed decisions, minimize financial risks, and efficiently allocate your budget and resources.

The best decision we ever made was to sell and 1031 into several properties in Florida.

If the financial analysis, including incentives and long-term savings potential, aligns with your goals, investing in solar could be a prudent decision.

What you do after you buy the house and which room or area you occupy is your decision at that time.If you mention to the Bank/lender that you plan on living in the basement for example or an ADU they can deny the loan.

That's a business decision. 

My two cents is to not let the financing drive your decision making.