PSA: Resist the temptation to buy that giant turkey. There are much better options.

I'm saying this from my personal experience over several years with turkey (and even some other cuts of meat like pork butt).

Years in the past I've gotten a little greedy at the grocery store and reached for the biggest bird they had. Turns out, cooking them evenly is simply a lot more work, if it's possible at all. We ended up with birds that were moist in a few spots and completely dry in others. Switched for a 12-14lb bird a few years ago and we've never looked back. Also gives us a chance to try some other fun options like just cooking breasts or legs on the side. They can be pulled off the smoker right when they are finished instead waiting around for the whole thing to hit temp. Multiple pieces also give you more space for rub and surface area for smoke! (The same is true for fried. We scorched the shit out of one years ago waiting for the inside to cook because it was too big).

TLDR: buy a smaller turkey, smoke breasts/legs, or even 2 instead of smoking a huge one. It's tough to get an even/juicy cook on a huge one.