Typically when you see "cash only" the agent doesn't believe the property can pass a home inspection which isn't relevant for construction loans in most instances and there are plenty of banks, hard money lenders etc. who offer construction financing on distressed buildings.

Just be prepared for potential vacancies.My advice is to build relationships with university housing offices.

They are tearing it down to build a logistics facility.

Running a portfolio well would be like taking on a second job as you build your own systems 

Best way to detect this is to observe them during the home inspection.

Hi John,Welcome to the world of real estate investing—it sounds like you’ve got an amazing foundation to build on, even if you’re just starting out.

Lastly, they like building relationships.

Regardless of the type of lender you work with, building a trusting relationship is crucial.

You can even learn a lot from leads that don't book with you, if you build report and ask the prospect worthwhile questions.

May not be your cup of tea but they are cost efficient and they work to add passive income at a fraction of the cost to build a SFH.There are a few "Tiny Home" builders in Tampa and Manatee doing a ton of business.