And to continue to rain sunshine on your parade..........
Don't underestimate the importance of the insurance issue 64 mentioned. Make sure when you research it you talk to an agent with LOTS of experience in commercial insurance. It's not something your "normal" homeowners/personal auto guy will be up on.

Along with Dave's comment, you'll need lockable/secure storage in each bay otherwise there'll be lots of whining about tenants stealing from tenants.

You'll need a "policy guide" to hand to the tenants, along with their signed agreement with all the terms, both rental and operational.

You'll need a process to boot out or seize property of someone who decides to use you as storage because they over estimated their abilities/wallet. And you'll need to be willing to exercise that process without reservation.

Just like the guys have said, this isn't a new idea, and it's never sustained. That doesn't mean someone won't come around some day and figure out a way to make it work. The closest I've seen for success in this type of deal is where the guy rented primarily to "professionals", basically guys who'd worked as body men, painters, mechanics, and either couldn't get along with others, or wanted to venture out on their own but didn't have the finances to start a full blown business. At least those guys were motivated because they needed the income, but on balance it should be said that most of them didn't have the dicipline to "make it" long term. A few did use it as a launch pad for a free standing, legitimate business. All in all, that meant turnover.......but that's what rental space is about.