Here in my areas of NJ the 'sign' must have a UL label.
As to the sidewalk inspection; 99.9% not a chance in hexx. They are up when we get the call.
'Signs' (boxes/channel letters) are usually not a 'problem', it's the NEON work (outline lighting & 'skeleton neon') that's the problem children.
BTW, do you have the mysterious midnight sign & neon guys in your area, or are they a NY metro area anomoly?? Leave a strip mall at 3:00PM, happen back at 7:30AM, and 'poof' there's a new neon install!!