Gitary, this technique sounds more like a dry brine. If you have too much sugar too early in the cook, your meat will be a nice shade of black and probably have a nice burnt taste. Bourbon spritz is good, but I prefer to drink the bourbon and just spritz with a combo of apple juice and apple cider vinegar. When I foil, I put the usual brown sugar, more rub, butter, apple juice in with the ribs. I have also put BBQ sauce in the foil and it comes out pretty good, but will tend to darken them up a bit too. You can certainly put your rub on overnight, I don't typically rub until about 1 hour before I put them on to cook. But this is one of the great things about BBQ, everyone has a different method, a different flavor profile, different smokers, different woods of choice, but it's all good!
Happy smoking!