And get lockboxes for the thermostats.

I also do not have a thermostat to my heat in the unit which leaves me no control over that.

Also, does any owners of units simply go through and replace the anode, thermostat, and heating elements for less then $100 in materials and find that has proven to be a solution to get the units to last another 7 to 8 years?

There are lots of smaller details too - thermostats for example - that I omitted to try to hit on the biggest cost factors.It is a doable project, the difficult decision is whether it is financially feasible to do it.

We also wire double poled thermostats to the units as these on the base units usually become defective after some time. 

These systems allow the homeowner to have the thermostat set 10 degrees higher than a traditional ac and have it feel the same temp, without drafts, hot or cold spots and large duct openings. 

https://insulateyourbuild.com/https://www.hunterpanels.com/product-over/wall-products-overviewhttps://www.buildgp.com/thermostat-radiant-barrier-osbhttps://www.buildgp.com/denselement-barrier-system2) remove siding and use spray foam.

Chicago controls auto set back thermostats.4.

:p  Routers in two of my properties have begun resetting to defaults, which disconnects my wifi locks, thermostats, smart TVs, etc.  

depends on tenant age, maturity and previous home ownership history. pellet stoves generally very safe 98% shut off with no electricity so not great safety net in grid down storm. and flame isnt open to being touched and can be controlled with thermostat   but as with everything from tub, pool, gym, ensure they sign legal form, require renters insurance, get your agent to include it and have lawyer draft a memo and add basic training every heating season. i am looking switch over my oil to pellet wood boiler fed by auger but its auto feed system in basement.