Use sunset as your turnaround alarm.
This is a lake-hopping trail more than a destination trail. Fehr, Shepard, and Hoover sit close enough together on 3.4 miles that you can turn around at any one of them and still count the day as a success, which is why it works with kids who fade unpredictably. The Division of Wildlife's own advice for the High Uintas is that if one lake is not producing fish, move to the next one, and this route is laid out for exactly that. Everyone parked along the Mirror Lake corridor needs a recreation pass.
Hop lake-to-lake (Fehr, Shepard, Hoover) casting for brookies.
Water bottle, sunscreen, hat, snacks, comfortable shoes.
Make it a weekend: Mirror Lake Campground (Camping, 0 mi) · Mirror Lake (Uintas) (Fishing, 1 mi) · Moosehorn Campground (Camping, 1 mi) · Trial Lake Campground (Camping, 4 mi)
More hikes nearby: Bald Mountain (Hike, 1 mi) · Lofty Lake Loop (Hike, 2 mi) · Ruth Lake (Hike, 2 mi) · Amethyst Lake (Hike, 8 mi)