Happy birthday. Stop by the Rendezvous Tiki Lounge on the corner of 52nd and 17th in Kenosha and I'll get you ****ED UP DRUNK. And then you can hit on the criminally attractive bartender.
One can assume that he did not park in the garbage hold, but timed his launch from the hanger to allow his ship to drift into the garbage unobtrusively. The same way Han timed his release from the back to the Star Destroyer to allow him to drift away unnoticed.
It actually begs the question about why the Millennium Falcon has a means of scanning its own surface but a Star Destroyer does not.