From his company's tower
Step 1 - Funding
Since the original question did not specify Stack Guy's flying speed, I'm assuming it is in the realm of Superman's speed; a.k.a. pretty damn quick.
The first thing Stack Guy needs to do is fly to the asteroid belt. Find some asteroids with high concentrations of iron, nickel, gold, silver, etc. Bring them back and sell them for a couple of billions dollars (if not more). Now he has initially solved the "I'm not rich" limitation of the initial question.
Step 2 - Headquaters
Stack Guy sets up own company, Stack Guy Industries (SGI). He picks the city and neighborhood he wants to most directly influence. He buys the right parcel of land. And then he builds the Stack Guy Industries Tower (SGIT).
The SGIT is a sixteen story commercial and residential complex. (Sixteen is used for an example, the actual number of floors and their composition may vary based on Stack Guy's funds, needs, and expectations.)
The first floor is a full sized grocery store (Cub or whatever other large chain he can get). They get to use the space rent free, in return for keeping their prices low.
Floors two through five are SGI's office space. A cube farm, conference rooms, and other manager and executive offices.
Floors six through ten are research space. Some more conference rooms and offices for the scientists, but mostly various laboratories.
Floors eleven through fifteen are apartments. SGI employees are offered living quarters as part of their incentive plan, for two basic reasons (outlined below).
Floor sixteen is Stack Guy's penthouse suite, office, and primary executive conference room.
And SGIT has a secret. All of the apartments on the fourteenth and fifteenth floors have a secret door, leading to a hidden staircase, which connects to the hallway between Stack Guy's suite and the executive conference room. Stack Guy told the designers and builders it was so his main advisors would have access to the top floor in the event of a power loss or hostage situation. He also implied it was because it wouldn't be a proper hero hideout without a secret passage. He further implied that he might want his cute CTO to have private access to his room (and verse vica).
Step 3 - Human Resources
Hire SGI personnel.
Crisis Monitors take phone calls, listen to police band radios, watch news, and monitor the internet and Twitter. Stack Guy doesn't have super senses, so he needs some way to figure out where crises are happening.
SGI, and Stack Guy himself also needs a team of Lawyers. Someone is going to sue Stack Guy, and he also needs someone to negotiate contracts for TV appearances, merchandising, and non-crisis assistance (i.e. Stack Guy can hire himself out as a rocket replacement; he can carry modules to the ISS faster, safer, and cheaper than a traditional launch. Only saving the world is pro bono).
SGI also has a team of scientists. They have two jobs. The first is traditional research, SGI tries to make the world a better place by more than just sending out a flying brick to punch things. At the same time, Stack Guy might need a scientist advisor on a specific emergency; how does he stop an erupting volcano, or melting nuclear plant? Because of that, the scientists are more strongly encouraged to live in SGIT, so they are on hand 24/7.
Beyond that SGI will need IT, maintenance workers, publicists, HR, and division managers.
Step 4 - Bring it all together
Stack Guy only ever appears from SGIT. Usually flying off the private deck on the top floor, but sometimes through the front doors for various reasons.
Meanwhile George T (Stack Guy's original/secret identity) is hired on by SGI in whatever mid to high ranking job best fits his skill set and work history. Whatever position it is, it comes with a fourteenth floor apartment. So now George can sneak back and forth between his apartment and Stack Guy's suite. And he (and dozens of other people) have a plausible reason to live in the same building Stack Guy always appears from.