Thanks to all who helped! I knew I'd get the hints I needed from this forum.
I can now rest at night knowing the current draw has indeed been fixed. The trunk lamp is 10W (!). Thanks, Arthur - you reminded my of I=P/V. 10W/12.6V = 740mA. Joe - I pulled the lamp and retested just to verify the math and it is right on - the draw after all systems reset and without the trunk lamp on is between 50mA and 90mA.
Interestingly, when the trunk mount CD changer is plugged-in but turned off, there is a small additional current drain of 50mA or so. Anyway - the total current draw is now less than 150mA in all conditions so we've verified that the original problem has been fixed.
2003 AMG S55