That way you can cashflow while living in your home and maybe in a cooler neighborhood than the 3-4 unit.

You’ll need to sell some food, sandwiches, muffins, etc  too I would think....coolers, display cases/coolers, dishes, dishwashers, supplies, costs for labor, rent, utilities, insurance, licenses, permits, inspections, etc, etc.

Think certain freezers, coolers, affixed displays etc. 

Just make sure they are understanding and I bet it'll be fine.If you have balancing or control issues - meaning if one space is significantly cooler or warmer than another - you can fix that pretty easily and cheaply but just installing in-line dampers in your registers or in your duct system. 

"Swamp coolers" work well when the humidity is low, but during our storm season in late summer they will not cool enough.

I manage in Barstow Ca, I think the climate is similar to Arizona where you are, I install window swamp cooler, those guys cool up to 1200 square feet house very effectively n the power consumption is s no more than a typical appliance.

Also, 3 of the 4 units have swamp coolers which the current tenants are fine with.

If your tenant has less to legitimately complain about than the rest of the people s/he works with, sooner or later you're going to end up with a waiting list of future tenants.I like this post and agree about the water cooler analogy.. when I had a bunch of rentals in one community that were almost all hud the tenants would talk and say hey I want one of those JLH houses..

It was getting cold he said ok I also explained to him the outside ac  fan had a Edison summer saver plans which turns the fan off at certain times he under stood but wanted the box off so I called Edison And had the box taken off problem solved .a week after  i got a call from tenents saying they got a message via text from the water company stating continuing runner water possible leak.so I went noticed they were running a swamp cooler 24/7 they said the ac bill was high so weve been using a swamp cooler,and they filled up a above ground pool .i asked them did they call the water company to let them know of the pool fill up they said they didn’t.i called the water company to talk to them about the running water text my tenants got and explained to them  they run a swamp cooler that runs on the water faucet and they fillled a pool ,and all the household water use from  big family.the water company said that’s why there getting that text.they also said that for me to talk about there account water usage they have to call and give permission so I asked the tenants they refused.its gets better,I get another call from the tenants now sayin one of the toilets are making a noise.so thinking the worst I go just a stuck handle.so while I was here I th ought I might as well change out  all fill valves and floaters for all three bathrOoms so I did.was there a few hours making sure they were running properly and leaks.i remind you that was on a  Thursday.on Monday my tenants send me a bill via picture text from  a plumber saying all toilets leaking cleaned out all fill valves because they were clog and put in new flappers leak fixed.i asked the tenants why’ didn’t he cal l me he  had no excuse,so  I called the plumber he said they clogged  and he cha changed the flappers.so i come  Back how’s that if I just put all of that new four days Pryor on Thursday he couldn’t answer me free.now im getting I’m not  paying  my water bill because of the leak.now they sent me there water bill .with previous charges from there old residents claiming it as part of  a leak.do they think I’m stupid,there clearly trying to scam me.they won’t  Give me permission to talk to the water company and  the plumber is his good friend.

It just looks like you made an upgrade... adds a bit a character.One other consideration, if you install a high-CFM exhaust fan, consider moving it away from the shower, like over the toilet.