Technically, your Surly Pugsley or Moonlander fatbike was made to carry a rear bike rack and panniers. But really, it wasn't meant to. And your panniers will never admit it, but they really don't like singletrack much.
Instead, maximize the carrying space in the fatbike's front triangle with a frame bag made just for the space.
A frame bag is a softer sort of bike rack -- an alternative to panniers on a rear bike rack. Carry gear, clothing, food or a hydration bladder. What gear? Your wallet, keys, cell phone, tube, pump, tools... For short trips or bikepacking.
The front triangle is the ideal spot for weight distribution for improved handling -- and a frame bag is just the thing for that spot. They are lightweight and keep your cargo centered low between your wheels and body.
Made of Dimension Polyant VX 42, a synthetic sailcloth. Durable, rip resistant, and tightly woven and laminated to make it highly water resistant. Not waterproof; we recommend using drybags inside if you risk riding in extended downpours or underwater.
Quality YKK brand water-resistant zippers get you inside. The large main compartment has a flexible divider inside, as well as a a hidden pocket. A smaller compartment is perfect for things you'll need to access quickly, like your map, phone, hard boiled eggs, uncontained pudding, marbles for playing marbles, your dugout, that ring you found that makes you disappear when you put it on, etc.
The front is flared a bit to maximize cargo space, and also functions adequately as a downtube wheel spray skirt.
This pack will last you for many miles.
NOTE: Frame bags will wear your frame's finish through repetitive rubbing as the bike is ridden. This wear can be minimized by using clear tape where the frame bag comes in contact with the frame, but cannot be entirely avoided. Wear to your frame from a frame bag is not covered under warranty. As Revelate says, "A bike that gets ridden a lot should look like it gets ridden a lot!"
Surly Nice Rear Rack
Surly Nice Front Rack
Salsa Anything Cage