Ive never taken temp on any of my fatty's. I just smoke it at 225-250 for at least 3 but no more than 4 hours and pull em off. I usually do them by sight. I wait for the bacon to become nice and dark brown and crispy. But thats just my taste. Good luck! I LOVE a good fatty!!
Well, it's not too late to start. Although I would say at those times and temps you'll probably be okay. Nice to be sure though. Only takes a seconds and it beats the hell out of crapping it out at high velocity the next day.