Well, you can put your self on the federal opt out list here:   https://www.optoutprescreen.com/This might be great time to do it as if you have purchased any property within 23 or 24 you likely will be in the money to refi already or soon.

I have learned that self management
 is not advantageous to most parking owners. 

I self managed out of necessity because my area has no fully operational property managers.

In order to get started just make sure you have high enough W2 or self employed income that you can qualify for the monthly mortgage plus savings for the down payment and closing cost.

Is there a DSCR loan available for refinancing self-storage properties in the $700,000 to $1 million range with a reasonable interest rate of 6.5% to 8%, or are DSCR loans only for residential investments?

Self-managing a large number of rentals becomes a full-time job.

I highly recommend reading the BP books for self-education and house hacking a 2-4 unit property for your first deal.

The catch is the self-sufficiency test. 

I'm an avid reader of BP but I'm also a self-taught investor like many of us here, barely 3 yrs deep into REI, so I'm certain blunders abound.

@Jessica Cheung - I would first reach out to your local Oxford House chapter and introduce your self.