I assume it has sewer/septic, water and electric and they 2 tiny homes are plumbed/wired?

.- increase in vacancy to 30%, 40%, 50% (this could be a combination of bad luck: one unit water damaged, one unit tenant trashed, and you have to evict two more - on a 10 unit portfolio that would be tough, even though only temporary)- lower rents (for whatever reason, what happens if rents go down 10% or 20%?)

If you have a 6 bedroom in an area that does not have a university (students looking for shared space) or is in a family friendly place it may sit vacant longer between tenants.For Capex, try not to use a generic number - look at the roof, furnace, hot water tank, kitchen - when will each need to be done and what will it cost?

With the lower price point rentals, you basically just tread water.

Still, if you’ve got someone on the ground who truly knows how to navigate these waters, it’s like being handed a map with all the back roads highlighted.

Its extremely important when running tighter margins like what you're talking about to focus on age of HVAC, water heater, appliances, roof, etc.

In addition, I will also be paying much closer attention to water flow patterns and signs of erosion around our next investment!  

Over a weekend during which my tenant was not home, the condo became flooded and water went through the flooring and flooded the office below.  

Given this is where my major operating expenses fell (beyond taxes and insurance), keeping this cost lower, by average, helps my cash flow.I invest in older neighborhoods, so the 2-4 unit properties, typically have single water meter, maybe single electric, and many have radiator heat with a single boiler.  

The rental might be vacant for a month,(8% loss) or a tenant might not pay for a month while you pay to evict them.(8-16% loss)  A $1,000 appliance/water heater, or a $8k rook or hvac unit might go out.(5-40% loss)  You should be paying a PM 8%.