Even on a $30k house, I need $7500 plus escrow and $10k-$20k for rehab.

I put lithium batteries in 2 houses in November and the battery is still showing 100% today.

We have a lot of money tied up in the unit and would like to find a rental unit the we would consider living in at some point with a house hack option/ADU and or a home that has a better long term appreciation potential. 

Here's how you can find good deals on properties that might need some work or are priced lower than usual:Connect with People - Make friends with real estate agents, lawyers, and others who know about properties that need to be sold quickly or aren't in great shape.Reach Out Directly - Send letters or use websites to contact property owners who might want to sell fast.Look Around - Drive or walk around neighborhoods to find houses that look like they need fixing up.

Is it worth buying down your mortgage rate?

We do have access to a HELOC on the property which we leveraged to purchase our current primary residence (balance borrowed has been fully repaid at this point) but we would rather not pull that lever to roll into a new property given current interest rates and the adjustable nature of the HELOC. 

If you're planning to hold and rent it out, you can refinance  to get a better rate after some months. 

If none of the above work, would it be so bad to sell the house? 

Additionally, you'll have access to less competitive rates, usually. 

This almost seems like a loophole, that I could buy a house which had multiple rooms per unit.