That's pretty much the way to do it.
That part is designed for a 1" barrel anyways (i.e. the thick part on autococker barrels where either pump arms or old school shrouds used to go), so a CF barrel typically isn't going to be thick enough anyways. I'd thicken the barrel up with whatever, and maybe cover that with shrink wrap or something to tidy it up.
Say, do you have black filament? You know how I likes my black...