Purchase price: $825,000 Cash invested: $50,000 3-unit owner-occupied building in downtown Plymouth.

Research owners and connect with them.  

I believe in my state if a prior owner lived in the property they need to be served in person which many times is not possible.

However your situation becomes a trickier case study since these properties first served as your primary residence which could provide additional benefits form a tax perspective not available to an owner of investment real estate and nobody has a crystal ball and knows the property with certainty will transition into an investment property. 

We first negotiated a lease to have a "first-right-of-refusal", then when the owner was ready to sell we purchased How did you finance this deal?

This has been the trend recently and can definitely cause some booking anxiety for owners. 

Called the current owner as it was not for sale.

You have enough equity in either property that either can be used for the ELOC but there are much more options on ELOC for owner occupied then investment properties.  

Keep at it, and you'll soon be the proud owner of valuable properties!

It seems like every town I look in has such strict regulations where you need to owner occupy your unit.