Are you locked into the thermo being mounted in the center section?
All of them that I have done have been in the dome opposite the vent. I get pretty good results, and the probe is usually out of the way of the food. A thermo in the center section won't be.
If you go with the center, I'd go woth the longer probe. The shorter one might have a negative impact on accuracy.
Whatever you do, mask off the area where you're gonna drill and drill at lower RPMs. Helps to limit porcelain chippage.
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