I have a old fly fishing vest, fits under any hunting jacket. Not hot on those warm days, holds a lot more than you'd think. Has a large pouch on the back. Hunting, fishing, hiking, quading it's first thing I reach for before going out the door.
For the hunting a small fanny to go with it.

If I'm going in someone else's truck I have small duffle bag that can be used as a pack. Stuff in it can get me by for a couple of days.
All 3 are always ready to go.