The closest I can get to approximating that type of "glen" in the US is a caubeen. The Irish Army "glens" are essentially indistinguishable from the green caubeens at glengarryhats.com, including the tails worn loose, with the exception of the saffron band & tails. I've seen some pictures of NCO's wearing them with the rosette and hackle centered and pulled down on both sides; unique, but not a look I prefer.
If I referred to mine as a glen among pipers here (99.9% of which wear British MoD style glengarrys), they'd suspect me an idiot.