>>1917982My layers are: wool long johns, softshell pants, uninsulated hardshell pants, optional gaiters. Should be good in movement down to -40 without a problem. Preferably have venting on the shell pants to be able to dump heat so you don't sweat too much.
Yeah, for camp you need a reinforcement layer over top. Same way you throw on a down puffy and down booties when you get to camp.
I have Canadian army surplus fleece pants I got for $7 I often use over/under those other layers depending. That adds a good amount of warmth, so sure you can use some sort of synthetic, high lofting pants.
Colder temps or when I need something lighter I have "below celcius" full zip synthetically insulated pants from MEC but they're kinda shit. I wouldn't really recommend them.
Pick a brand and it should have insulated pants. I'd definitely suggest full opening side zips though so you don't need to remove your boots/layers.
Synthetic: Rab Photon, Patagonia Nano-air/puff, Mountain Hardware Compressor, Helly Hansen Lifaloft, Arcteryx Atom LT pants (discontinued, might be able to find LEAF version still)
Down: Rab Argon, Mountain Hardware Ghost Whisperer, The North Face Summit L3, Sitka Kelvin 3/4,
Other: Smartwool Smartloft (50/50 merino/polyester insulation)
Smaller brand options if you prefer: Taiga (Down, Vancouver), Feathered friends (Down, Seattle), Stone Glacier (Down, Montana), Western Mountaneering (Down, California), GooseFeetGear (Down, USA)
Cheap option: Go on Amazon and just type in 'Down pants' or 'insulated pants' and pick one that looks okay, return it if its shit.
Another option is to just bring a wool/down/synthetic/fleece blanket, cover your core+thighs at camp and you should be fine.
