My system hasn't changed much in a long time. I use pretty much the same from spring bear through late season.From late October to December on hunts where I hike in the dark, get to a spot, glass for a few hours at daybreak then move and glass all day I pretty much have my BL figured out, But I am constantly changing what I take for a second layer. Most of the time this is my outer layer till I stop to glass. What are you guys using?
Baselayer - Short or long sleeve merino (usually about 150 weight)
2nd layer - Fleece or a Merino blend, my favorite is the Sitka Fanatic Hoody. (only complaint- tight sleeves)
3rd layer - Puffy vest unless it's really cold and I put a puffy jacket on and then the vest. My favorite is the Kuiu Super Down ULTRA Vest. I also like the Sitka Kelvin Aerolite but it's not as warm.