Any marketing should always be based on the information provided by sellers in a deal. 

I want to reach out and get feedback on where I would be able to find off market self storage facilities and how to approach the owner?

My easiest, no hassle, lowest expense rentals are the ones where the tenants stay 5 + years, do minor maintenance themselves, call me immediately with any issues so I can fix them before they become much more costly, and agree to annual market adjusted rent rate increases.  

I recd a bunch of marketing flyers from them last week

Unique neighborhood and product within local market.

The property has remained 100% occupied throughout my ownership and is on track to continue receiving market rents from both tenants.

The property has remained 100% occupied throughout my ownership and is on track to continue receiving market rents from both tenants.

Marketing-Ready Design – Your rental should look as good on camera as it does in person.

There are plenty of older homes on the market that do not have closets.You need 2 egresses (including 1 that goes outside) such as a door or window, size about 70sqft (local codes may differ), ceilings at least 7ft high, and it cannot be a walk-through passage.As always, your local codes may be different.

The STR market here has become way more saturated and competitive especially in San Juan.