I am looking for a front platform rack for my Salsa Mukluk (fat tire.). Something similar to the Racktime I have on my Safari (pictured below.). I want to take it on some multi day tours. I do not use low riders at all but do tie my sleeping bag on it. Any help would be appreciated.

Specialized has had one that comes apart, in 3 portions, flat-ish to ship the bike.. as I recall /

but whether it will fit over fat bike tires IDK.

Have you looked at Origen8? It attaches to the caliper hole and has telescoping (adjustable) legs to attach to the front axle.

Old Man Mountain makes some fat bike racks.

Front Fat Disc - Old Man Mountain specializes in Racks designed to work on all bikes.

Surlybikes 8-pack or 24- pack rack. Depending if you want a little wider on top, or more like a porteur style rack. Fits traditional up to fat tire bikes. Cargo | Parts and Accessories | Surly Bikes