Honestly even if you’re trying to operate your rental property as a ‘non-profit’ you’re still going to wind up in trouble if you don’t ’over-charge’ to build up a repair / emergency fund for the property. Such is the cost of owning a house - unexpected expenses may cost tends of thousand dollars, and may not be possible to put off, even legally, nevermind ethically.

The cost of ‘what if the roof caved in tomorrow’ or ‘what if the furnace blew up’ should be built into the rent.