They tend to all have good incomes, little to no credit, and are self employed with lots of family.

Are you self managing those properties?

I am planning to self manage as well and since there aren't many managers in my area I will likely employ a similar strategy once I decide to outsource the management.

I pay self employment taxes on myinterest income from mortgage notes because I am considered a “dealer” and am in the business.

Most people self exclude themselves. 

Does anyone know a property manager that supports small self-storage rentals in addition to residential rentals?

I say that because every decent legit place I know of in market, yes offers the option of doing just tenant placement, for self-managing. 

A realtor can send you a walk through 360 which can be good enough to get in on some listings to make an offer.Once you make the offer fly out and do a personal walk through and then figure out do you want to self manage or hire a local manager.

This guy could come up with a self-serving reason for everything he did.

Where is vacancy, maintenance/cap ex, asset protection, PM (include it even if self managing as you deserve to be compensated for your efforts), utilities, misc.