As a Real Estate professional you should know about:  Lease with Option to Buy, Contract for Deed, Rent to Own. 

Hi, I just leased to a new tenant (six-month lease) and the tenant has moved into the premises this month.

The house was built in the 1930's about the same timeline as the previous house I just rehabbed and rented (Pushed about 40K of equity depending on the appraisal, and only spent about 13K for the rehab) the ARV on the new triplex is about $230k with about $10-15k, all together worth of rehab work as each tenants leases come up, and I'm talking basic interior paint, some vinyl floors throughout except bathroom, and any nick-nacks throughout the units, not a full scale rehab as I did before. 

The other 3 are long term leases and the 4th is a furnished STR that I have been seasoning since March.

My initial thought was to set up a master lease option until the mortgage is paid but 15 years seems excessive.

As a leasing consultant for a property management company, I usually see tenants pay all utilities. 

Have you considered getting a job with a developer maybe starting on the leasing side of a new construction building and get an understanding for that side of the business and see if there are future opportunities in the property management then development side?

Their leases are up at the end of Feb 2018 and as far as I know they have not renewed.

We have a lot of equity (about $350k) and are looking for a better investment.My plan is to sell it in June when our current lease is up and 1031 for two 3-families around Boston.

Go on Craiglist and inquire to a few people about long term leases, see what they charge you.