Kids to camp at 2:00, wheels toward the trail by 3:15. Every time below is re-cut for a fast pace so you bank the hatchery view and the full Fire Tower loop with real daylight to spare.
Missouri state parks are free — no day-use pass. Grab a paper trail map at the Nature Center if it's still open when you arrive; the loud pyrotechnic vulture deterrent near Campground 3 only runs ~8–10 AM, so it won't affect your afternoon.