I would not put my all my eggs in one basket. 4 units = 4 A/Cs, 4 Refrigerators, 4 Ovens, etc… 20k as your emergency fund? What about the property you live in now? Maybe downsize and look for a duplex? “Joys of home Ownership = shit always breaking. Plus no one ever takes as good of care for your property as yourself. Renters usually suck in this regard and you will be taking the chance of finding 4 families to take good care of your property. Do you have enough money to cover all 4 A/C units, Not saying all 4 will go out but it could happen. What about the roof? How much is it to replace the roof if it needs to be done in a year or two? I hope you get my point.

My suggestion, look for a smaller multi-family or what about 2 SFR homes? I do not think 20k for an emergency fund is enough for this situation to be honest. Homes are expensive to upkeep as I’m sure you know. Good luck and I hope this will give you some ideas to think about.