I agree those options can also be effective solutions. If you try that, there are Miflex swivel hoses available, so you can reduce the amount of brass you add with a separate swivel.Not sure why you are interested in the custom mouthpiece, but I was thinking about one several years ago to reduce jaw strain. Instead, I switched to a more flexible hose (braided) and added a swivel connector between the hose and my second stage. Now I hardly need to use my teeth at all to hold the regulator in my mouth.
--Thumbsplitter