Although its recommended that a bird that big should be spatchcocked, I have done whole 23 lb'er on my vertical gas smoker. As for tips, it must be brined! I would stay with the smoker until it reaches that safety zone temp. Make sure the temps stay steady in the range that you want to smoke. Use a reliable digital thermometer, one probe for the cc and the other to monitor the bird. If I recall the first one I did, I hit the 140 IT right at 4 hours and the smoker setting between 225 and 235. I did begin to worry at the 3 hour mark and was only at about 130 or so and allowed the smoker to hold 235- 240 until that 4 hour mark and reasoned that 135 would have been ok at the 4 hour mark if that was to be the case. The bird turned out great and have done other birds of comparable size and never spatchcocked any of them. That is what has worked for me but a bird that big, just be careful to insure that it is done throughout! For the record, had I known about spatchcock when I did my first turkey, I may have done it and continued to use it. I am comfortable doing big birds whole!