I have both options,... a hole to sneak cable thermometers (both pit and meat probes) inside and I also mounted a 12" long thermometer a couple of inches below my upper grate to measure the temp in the center of the drum. My drums have a 40 to 50 degree difference in temperature readings between the short stem thermometer and the long stem thermometer, so I rely on the long stem one.
I have a small shelf for my cable therms, plugs and to hold my wiggle rod, the bottom photo was taken before I added the second thermometer.
KCBS - CBJ
Big Green Eggs, Big Drum Smokers, Big Chiefs, Weber Smokey Joe "Custom Tall Boy"
Oil Patch Horizontal
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Barbecue is not rocket surgery