Here is a brine that has great reviews. I might give it a shot this year then lay bacon over the top of the breast while smoking.

Slaughterhouse Poultry Brine By Tip Piper of Hillbilly Vittles
1 ½ Gal Water
½ C Salt - Kosher
½ C Dark Brown Sugar
2 tsp Garlic Powder
2 tsp Onion Powder
2 tsp Cajun Spice (Louisiana Cajun Seasoning)
2 tsp Celery Seed