You could also use 25s instead. For the cape you'd have to CO more stitches, but wouldn't be difficult for this pattern. Figure out your sts per inch, then how many inches the CO sts in the pattern makes and multiply your gauges times inches.
Yeah, I was thinking I could adjust for 19s if I couldn't find further use for the really big 'uns. I'm not sure what else I'd do with 25s either to be honest.
That's a cool scarf, atroxsilentium.