In a Form 1 you can rotate the baffles and adjust the blast chamber for decent spacing off the muzzle. So I’d go with a functional flash hider for when you shoot without the can and design for that (larger bore, fewer spaced baffles like a Turbo K, all heat treated 17-4 baffles, maybe even a flash hider front cap). This is in recognizing that a 10.5” 5.56 will be loud anyway. If it’s a .30 cal or larger can then the minimalist Turbo K arrangement is less than ideal. Although the Sandman K and one of Rugged’s designs only have 3 baffles. Buy spare cones and spacers in case you screw a few up in fabrication.
The Griffin XL adapter also lets you effectively lengthen the blast chamber for a little more weight and cost.