Beyond that I do need it to be pretty self-sufficient.

I'd probably have sufficient funds available to add either another Duplex or 2 more SF later this year. 

Every few days there are new issues and we are constantly having contractors and technicians at the house dealing with one problem or another, while coordinating with our tenants who are on a range of work/sleep schedules.

.: @Jason Phu you haven’t provided sufficient info so you’re going to get a lot of incomplete responses.

We have the lot.Quick background: we built a 4 bedroom (sleeps 16) in 2021 and it's doing great. 

I have a once triplex converted to a duplex that I’m turning back into a triplex . hope that didn’t get too confusing.So I’m trying to figure out the best way to supply all 3 units with sufficient hot water in the most economical way of course.

No one has used it yet.Our house is new construction, sleeps 16, in Gatlinburg. 

So if you want to maximize your revenue, find a house with larger bedrooms so you can sleep more people and charge a higher rate.

Don't sleep on the new changes to Fannie's requirement for downpayment on 2-4 unit multi either.

(Again, check your local laws to make sure this is sufficient.)Also - unless the laws under which you operate say otherwise - you are "notfying" them of the increase.