Take a look at first pick here. This is a similar situation, difference being i built the surface surrounding the monitor. rough up the surface of the both bezels. Tack the monitor to the bezel. CA glue (super glue) works well. Then build a surface for your filler to sit on between the gaps. Whether you use popsicle sticks or card board, doesn't matter. Now Choose your filler... this stuff is pretty good. Spread your filler using the edges of the monitor bezel and the car bezel as a guide to create a uniform surface bridging the two.