I cannot for the life of me remember what these things are called. Not harem pants, but there's a kind of very, very loose-waisted, one-size-fits-all, baggy south or southeast Asian trousers. The waist will be something like fifty or sixty inches, but it's meant to sort of half-wrap around your body, then there are ties at the end that can be used to fasten it. Legs are pretty huge as well. Anybody know what I'm talking about? Trying to google them, but I keep getting either form-fitting yoga pants or I Dream of Genie harem pants....
This is something that comes up in my searches as a type of pant. For Thailand, I get the pha sarong, sampot, and pha chong kraben. Dhoti (Southern Asia) is another type of pants/lower body covering that I found. Maybe one of those are what you're looking for?
Those are all close, and I might end up using them. The character is an American dude with a thing for the "spiritual life", so nothing is set in stone, but... Those are exactly what I mean! And the name is... Well, it gives me a place to start, thanks to everyone for their help.
According to Wikipedia’s listing for Thai fisherman wrap pants the specific name is kangkeng le, pronounced [kāːŋ.kēːŋ lēː]; Lanna: สะดอ, pronounced [sa.dɔɔ]).
In most of the Vietnam war books I've got they are just referred to as 'loose pants' - they are the bottom half of the ao ba ba or ao canh (the letter in the north of the country)
If, for example, your dude is interested in Japanese spiritualism but wears Vietnamese pants that raises some questions... So, the word for the pants and the pants themselves would depend on what sort of stuff he's into. If the dude just thinks all South-Asia wears the same pants, then that will make him look like a certain type of dude, maybe not the type you intended. Choosing which word to use is not really random.