That sounds like a terrific setup from the remodeled guest house, to the HELOC.  

Just técnicas from the David Green on his books Bua also I have experience on flipping and a extensive Construction career, specifically on out of state projects and logistics, but the be completely honest,  First time with BRRRR!!

To recap: Be extremely cautious with flat fee MLS sites that only refer business to other agents.Bonus PointsYou should also consider the ease of use of the flat fee MLS listing provider, for example, can you complete everything online?

@Namal Burman Sounds like you have an understanding of what you are getting into financially and location wise...go for it if this is something you are interested in and want to pursue. 

Some contractors even specialize in converting containers into houses.Wow I sound like a container shill.

They completed the project and now are working with their RE agent to get this property on the market.

There are two important things to remember here: first, you cannot selectively pick tenants without children, as that is discrimination against families in the state of Massachusetts, and second, you really need to make sure you can afford to complete the lead removal prior to listing it.

So from a capex perspective, it made sense to completely replace the exterior siding (and make it insurable).

Sounds like you have time on your side starting out before buying a single family house. 

Please note, you have to have the repairs completed to sue for them, the quote won't work.