Tony, fwiw, I only have one probe now too and I use it to measure temp at the lid. I don't temp my butts anymore. If you are worried about it, you could use an instant read like Mark said. On my cooker, in my neck of the woods, with the pork I have been using, this is what has been working for me lately: I cook at 250 at the lid and start checking the butts after 13 or 14 hours with a probe for tenderness, not temp. Typically, they have been taking between 14-16 hours at that temp. It will be a little hotter at the lower grate, so if you have any butts that are larger, put them on the bottom with the small ones on top. Good luck!