IF you are hiking in, I'd say down bag. I have owned Wiggys bags for 20 years and I use them regularly, but if room in a pack is important, I'd compress a down bag to half the size of my Wiggys (and it would weigh less than the Wiggys) to make room for food and fuel. That said, Wiggys is warm when wet, it will clean when put in the washer and fluff dried on low or just hung to dry with a fan directed on it. It is the most versatile non-down bag I have ever owned (I own more than one) and is almost indestructible.
4 season tent as you can easily see snow in Idaho in October and you don't want a drafty, cold three season tent that can't take the wind and loading a 4 season is designed for. Marmot, North Face --almost any big name mountaineering brand will do a credible job--I do a three person tent--knowing I want to store my gear (hang my food outside or in a bear-proof container away from the tent) inside with me rather than in the vestibule. I need room, I'm a stomach sleeper not a side or back sleeper so I'm 7 feet long with my big feet stretched out.
Have fun!