I know this is not sous vide, but I have had my greatest success using a pressure cooker for stock. Because it allows water to be superheated (up to 121C) it helps to break down the bones, collagen and connective tissues faster. I have made rich, gelatinous broth in just an hour with chicken bones this way. It also prevents excessive loss of water.
If anything, sous vide would take much longer than your current stovetop method and I don’t see it being any better.