The issue with the Stan character is that his purported hobby -- photography -- is the same as Axel's. There's stuff that you could put in a Stan arc with photos and exhibitionism, but you're already doing that with Axel. Stan needs something to make him interesting that isn't photography, drawing, writing or music -- that's all stuff the other guys do.Stan's problem is that there is really not much interesting that can happen in his path.
Easy-ish thing you could do is make him a wanna-be filmmaker. Trade his still camera for a movie camera. You'd have to make him a little more confident, but you could keep his character model and you'd have a lot of potential sideplots if Stan was trying to get a movie financed and shot.
Another alternative is double down on his nerdiness and make him some kind of hacker who into stuff on the dark web. That wouldn't fit the goal of trying to make another "good guy" option, but if you wanted to go for a hardcore corruption path, similar to the gang route in GGGB, that could be the avenue.
So I think you can do some things with Stan that aren't a complete re-write from scratch. You have to start by giving him some kind of core competency that makes him interesting and sets him apart from the other dudes.