Check your electric is sufficient to handle the new units and if those units would be on tenant electric you would need to compensate them until you were at lease renewal as they have a utility included and you would be changing to non-utility included which shifts the cost to the tenant.

They have completed construction and 90% of the units are leased up.

Since you have a month-to-month lease, you have flexibility, so consider negotiating with the tenant or transitioning to a non-Section 8 tenant.

How would I go about finding a sober living operator that could sign for a lease?

I've used Zillow Property Management for listing, background and credit checks (potential tenant pays for), leases, and rent collection.

@Pantelis Pantelides not sure if you found a solution but if you are out of state and looking to manage yourself but need on the ground help, a leaseing agent and using the platform hemlane is a pretty good way to go. 

Quote from @Clay Lyddane: I have been an accidental landlord for a while , took over a 600 acre farm in Kansas and have been leasing it out for about 20k/yr --no mortgage and about $1500 in taxes and $15/mo for water.

Management decisions that count as active participation include approving new tenants, deciding on rental terms, approving expenditures, and similar decisions.Based on this, then I am an active participate as I'm the one working on the lease renewal negotiations, sending out invoice, paying bills, etc. 

We used to own all of our houses but are about 50/50 lease vs. own, mainly because leasing allows us to move faster when opening additional houses. 

But you need to know what kind of lease structure they are offering.