Update on using heat sink:
Filled water tray with combination of sand and gravel, covered it with foil and placed under bottom rack on MES 30.
Smoked a bunch of wings, using wood chips in tray and everything worked out great!
Temp stayed solid, only losing 10 degrees when I opened door to rotate racks.
However, when I used the AMPS on a brisket, the tray seemed to limit the ability of the AMPS to do it's thing?
Almost went out a couple of times?
Not sure why, but when I took the tray out, the AMPS worked perfectly!
Good smoke came from it for 7 hours.