It might be that this couple that owns the house is just getting their feet wet with having someone else managing the property and they want to get comfortable with your management style as being what they want.

Individualized container homes would be ill suited for assisted living style care.

Upgrade to a commercial-style stackable setup that can dry faster (30–45 minutes), hopefully fitting in our existing laundry closet without extra electrical work.Any recommendations or specific brand/model suggestions for handling this high-volume, semi-commercial laundry?

I am in discussions to seller finance a townhome-style quadplex.

The goal of the first 3 deals will be to target 1-4unit styled homes, requiring minor-rehab.

Direct lenders are great for portfolio style loans, investors that do significant transactions and have a banking relationship. 

I think the biggest mistake that people make, is thinking that investing in STR´s is some totally different style of real estate. 

What is not helpful is the assumption that some responders made that the root cause is the PM's communication style was not to my "liking".

You'll likely find it easy to find people who will tell you what you want to hear, but you really need hard facts not speculation.But for some speculation, if you're talking about the Nantahala River or Little Tennessee, sure I think you might be able to do $22K/yr, but not much more, unless perhaps the places are uniquely styled. 

They could have particular styles or things that they specialize in and wholesale the rest.