We would be installing a street and double stacking townhome style units on each side.I part I don’t have experience with necessarily is how to better understand infrastructure and site work cost (road, utilities, excavating, etc.

I setup one QBO (Quickbooks Online) account to handle multiple LLCs. 

Theres a lot of place online to list like apartments.com, facebook marketplace, realtor.com, trulia, rent.com.

What's next pay their utilities for them.....? 

Go to Etsy and search for "rental property tracker," and you will find hundreds of nice spreadsheets to track 10-20 rentals, usually for under $10.Software has extremely helpful features like online payments, marketing syndication (click a button, and your property is advertised on multiple sites), electronic document review/signing, maintenance tracking, and owner reports.

I won't be charging him any rent, he will just pay for the utilities used for that period. 

Rent assistance is also provided by other factors such as number of bedrooms and if the Landlord is providing any of the utilities.

Sadly, it’s sat on the market too long and I’m looking to get creative with bringing the attention of many buyers looking for a good deal on a property (online auction or something else with tons of attention??)

We currently have 105 units and are using a variety of excel, google docs/sheets/calendars, apartments.com (ads and rent collection), docusign and QuickBooks online (which we would like to keep). 

Check out other online guides available here: https://www.biggerpockets.com/guides3.