I thought there were problems with the seacure mouthpiece both not fitting properly, and causing CO2 buildup because something something flow dynamics...

Anyways, I just did a 20-hour trip, and got a useful piece of advice. When sitting on the bench, the mouthpiece was pointed in, towards the unit. Someone told me to rotate the hoses so that the mouthpiece pointed up towards the sky. That helped a lot, and I didn't have cut lips the rest of the trip. Or maybe I just built up an embouchure, as suggested earlier.