Unpermited garage kit… how bad is this idea?

I live in California, in a Bay Area city where unpermitted structures under 120sqft are allowed, but obviously this isn’t large enough for a garage. There are *lots* of unpermited structures and additions in the area, and from what I can tell they are very rarely reported.

At the back of my house, at the end of my driveway, there is a large concrete pad that **used to** have a garage many years ago (unfortunately none of the structure remains, so it can’t be simply rebuilt).

I have previously looked into a permit for a garage, however code requires that I would need to tear out the concrete pad and re-pour it, as it’s a little too shallow (code requires 6+ inches, mine is about 4”).

I am considering - in the short term - putting a 240sqft metal kit garage on the existing pad (I currently have an awful looking tarp carport in this spot). It’s cheap (\~$1500), but would look **FAR** better than what is there now. I have no concerns with neighbors reporting this.

Worst case: If it were reported, I’d be fine just taking the walls down, reinforcing it, and turning it into a carport.

How bad of an idea would this be? What implications might this have with my home insurance? Anything else I’m not considering?