I'm fortunate I don't need the cashflow so the whole $400+ not going to debt service, taxes and property management stays in the account and grows over time.

Unless they're on a foundation, container buildings will be considered by banks as "personal property," and banks won't finance the main house if there's a "trailer" on the property when the next buyer takes possession.  

Wanted to get some advice from others on how best to harvest equity of single family homes that are currently free and clear of all debt.

If you are getting a loan from a friend or family member, it is a good idea to use an IOU note in case you need evidence of the debt in a court of law.

There is a property I am interested in, and it will be auctioned at the courthouse next tuesday, so I order a title search.It shows only 1 lien for $amount (I don’t know the current balance of the debt), originally taken out by Barack Obama and later the loan was assumed by Donald Trump when he bought the house from Obama.

I'm pretty sure Cash on Cash implies using debt.

I also owe about 20k in non-mortgage related debt. 

Likewise, brokers 'transfer' possession only after documents are recorded.

, or should I take an equity loan and go further into debt?

That debt will be settled out of my own pocket after closing.The moral of the story is to find a competent attorney that understands what you are trying to be do, so that all of the proper documentation can be created and filed.