I say this as someone who has little/no experience smoking turkeys, but I personally think 225 is too low to cook turkey for a couple of different reasons:
1. I would worry about the texture of the skin being too rubbery during a low and slow cook.
2. I don't think a turkey would have the fat content to sustain that long of a cooking a process.
The videos that I have been watching have the temperatures at least 275 (
Aaron Franklin, How To BBQ Right,
Chuds BBQ) . For me, I think I am going to run my smoker at between 300-325 but wouldn't bat an eye if it got up to 350.