It’s probably still a bad deal for the owner to install in more than about 10-15% of the assigned parking spots.

You previously commented that your own investments met all expectations. 

Are you installing new smoke alarms?

A quick google search turned up this: https://windowwellexperts.com/...You can install a legal egress window for $3,000 - $5,000.

We had the plumbing break down and had to install new PVC plumbing Did you work with any real estate professionals (agents, lenders, etc.) that you'd recommend to others?

I would like to install all wood cabinets as this house will hopefully sell in the low $200K's after renovation. 

Hunting leases are a popular way to generate steady income, especially in rural areas.Solar or Wind Leasing: If your land is in an area with good sunlight or wind, companies might be interested in leasing it to install solar panels or wind turbines.

I'm concerned that the combined load of heat pumps and ancillary heat strips, along with other appliances, might exceed the 100-amp capacity during winter.As part of our future plans to add a third unit and separate the utilities, we intend to install two additional meters: one for common areas and one for the new unit.

You could potentially install a mini split for the downstairs unit so they can control it themselves but that's a more costly remodel.

If you choose to sell, consider post-retirement timing, installment sales, or a 1031 exchange to mitigate taxes.