opinions/criticism wanted

The easiest best way will have to be the way factory would do it.
Get a rectangular light fixture (something like a corner lamp from a Lincoln). Something with a chrome frame. Recess the entire fixture into the door , killing panel and vynil around it. Then do what ever you wish to the lens. Black out all but the fish, simply attach a factory chrome fish on top the lens. Atleast you'll have a real light fixture and a way to access the bulb. The "oh chit" factor will be in rolling window down hits the fixture.