My tenants take care of the lawn mowing and snow removal, never cause any disturbances or have any arguments with each other or the neighbors, and always pay their rent on time. 

Additionally, in this county, there is a rule that if we disturb more than 5000 sf of land, we need to spend about a year in site development review with storm water management, etc.

Do not disturb the tenants.

Tag-lines run so many lives now, it's disturbing. 

Assuming you aren't disturbing the commercial tenants' businesses, I don't see a reason why they would leave. 

In a multi-family situation, there can still be requirements regarding pets/esa as in if the dog barks and disturbs other tenants, it can be dealt with.

Ma'am I'm so sorry I didn't mean to disturb you, absolutely I will take you off my list right away.

The biggest piece to closing on something off-market is being able to have an offer presented to avoid the hassle of listing- especially when there are tenants in place that do not want to be disturbed. 

Cannot disturb others with barking (unless alerting for a medical issue) or aggressive behavior.

Check your state/local laws for disturbing interior/exterior surfaces/containment/abatement/environmental (particularly if it will ever be a rental).