What temps do you use and for how long? Do you crank it at a certain point to get some crisp on the skin? I feel like expediting the process with spatchcocking would make the skin more rubbery.
You definitely don't want to go low and slow with chicken. 300-350 works fine, but you can go hotter if you want. Chicken's a fairly delicate meat, so it doesn't need a ton of time in the smoke to get the flavor you want. Definitely be sure to pat the chicken dry all around, but especially the skin. Then brush on *just* enough oil (or whatever binder you prefer, if any) to help your rub stick, no more. You don't want any more moisture on the skin than absolutely necessary.