Mr. Buzzkillington here... TG is not time to try anything new. Typical scenario is that the bird takes WAAAAAY longer than you anticipate and no turkey. That said, you will probably will do it anyway
so here's what I recommend: halve the bird and roast one half in oven and smoke the other. This helps you in a few ways.
I am with
chef jimmyj
and inject large items and brine small so I;d be injecting here. Heads up, you want a day or 2 rest for the injecting to equalize. For turkey, I suggest Pops Brine low salt version.