I think first of all cooking it on the bone is an excellent way to retain moisture not to mention flavour. Most places I've worked roast whole crowns (both breasts on the bone), debone and finish in a hot oven, rest uncovered in a warm spot. Sous vide is an excellent method to retain moisture but lacks the crisp skin of a good roast chicken. For sous vide try soaking it in seasoned buttermilk for a few hours first. Be sure to use a good product that has not been previosly frozen. good luck