I didn't use CVO mufflers on my '12 103, they were stock '07 off my (then) Road King. They had a wire screen wrapped with about 1/8" fiberglass and the assembly fit snug in the can. I cut the right side shorter to fit behind the rear mount ring but could not do that with the left side because that baffle has a mount ring up front, too (notched to pass by the axle dent). The cores I used where Fullsac's 2". The sound from the left side was too "resonanty" so I had to unwrap the wire screen "tube", open the staples holding it into a tube, cutting it to fit between the two mount rings, and re-wrapping it. Must've been 100' of continuous-glass-strand "tape" about 1" wide. That was ~5000 miles ago now and I don't see needing to get back inside the cans again for quite some time. The sound is perfect. The slightly-obnoxious quality is completely gone.
If your muffler cans have that sort of "packing" I'd use it. Maybe go to the hardware store and by some wire screen with about 1/4" openings and duplicate the assembly. Damping the can itself so it stays cooler and doesn't resonate is just the ticket.