No offense, but it sounds like you want some kind of pot roast. If that's the case, go for it. The whole idea of bbq brisket is low and slow and smoke. Sitting in a liquid, the smoke is not going to penetrate the meat all that well. The liquid might make a gravy with smoke flavor, but then again you're talking pot roast.
Personally, I'd rub the brisket with whatever type of seasonings you prefer and put directly on the rack. If you want smoked apples or onions, put them on a different rack.
All the Cookshacks and FEs cook moist enough that you don't need to braise a brisket. I don't even foil until I pull them off the smoker to rest. Some here foil later on in the smoke and add a little broth or other liquid at that time.