Are you building for pure investment purposes or are you looking to use some of the space for personal/personal business use?

How big is the space they are renting? 

I would also encourage you to look into the house hack space. 

If you can find a place where the HOA or COA is flexible and you are able to convince the membership to go into development and perhaps convert the property into a co-op you could build a new apartment complex with commercial rental spaces on the ground floor and residential spaces on the top. 

Are there any specific clauses I should include in a room-by-room lease for a shared living space?

This amounts to lost opportunity because if you had purchased RE, at the closing it can start producing return. 5) ADUs detract from the existing structure whether this is privacy, a garage, or just yard space. 6) this is related to number 1, but there are many more buyers looking to purchase homes for their family than there are RE investors looking to purchase small unit count properties.

That will allow you to build the additional legal space further amplifying the value of the proprety (more HELOC money). 

It is not a "data" thing.This is the actual reason why it is so hard to become successful in this space.  

because we have a strong demand for them and great str laws.The Triangle is visited year-round by travelling professionals in the research, medical, IT, and education space.

Two groups that I will consider investing with again are Colony Hills Capital for multi family and FNRP, which specializes in grocery and big box store anchored retail spaces.