I reduced my responsibility to only taxes/insurance while the tenant buyer does the maintenance, pays utilities and makes monthly payments to me. 

I was willing to pay more than my competition.

Must pay well, she door dashes breakfast, lunch, dinner like clockwork.

People in 1981/1982 were angry they were paying 18% interest.

It looks good) I stumbled across someone locally who does it, but I'm sure you could find someone there if you or other out-of-town investors like the idea of paying a bit more for that level of security and obtain a remote monitoring source of the exterior of the properties.

How much less will a potential buyer pay for the house, now that one "bedroom" does not have a closet?

You have to disclose all of this when you sell, so you will end up paying your plumber or discounting to your buyer.

both have 5yr pre pay penalty. 

I know this post is a little old and not sure if you went through with your ADU construction yet, but my partner does ADU ground up construction in the LA area.

The property owner's tax professional can help them with that and ensure they don't pay taxes twice on the same income.Disclaimer: My advice/opinion in this post is just that, my opinion.