The builder suggested a local bank that they use and would like to see them succeed and referred me to the commercial lending department.

Hopefully your lease has provisions that explain the process for adding a house mate/ how long guests can stay/ repurcussions for breaking the lease and I would reference those in your note.

Especially a meet up on private lending, ADU additions are discussed regularly (new attendees looking for money for their ADU additions without being aware that no one there will lend on ADU additions).  

By structuring deals with regular refinancing, you can unlock the equity in your properties and access capital for future investments.

They understand that there's value in what they provide, which is steady, documented income, minimal turnover, steady payment, quality references, no drama, and peace of mind.

Regular Conventional? 

I'd just make sure to check their references.

Everything else is a level of passivity vs. how much management and oversight you want.I will still have more active investments as well, but I think it's silly when passive income is referred to as part of say, multifamily.

Also for reference, pretty typical SFH flip type properties in my market are about $300k - $400k price tag.  

I think you are referring to the deed.