Problem is, a 3.0 plus size tyre is 70mm wide...not many mudguards can wrap around that. Probably need to be some kind of bodge where you cut the mudguard in half and rivet in some extra girth using flexy plastic...I've seen some "how to's" online for fatbikerz...
Gilles Berthoud mudguards have a pretty flat profile in 60mm. They might not cover the whole tyre, but most of the water gets chucked off the middle and they should match the curvature okay. And being stainless they'd be a good platform to modify
Problem is, a 3.0 plus size tyre is 70mm wide...not many mudguards can wrap around that. Probably need to be some kind of bodge where you cut the mudguard in half and rivet in some extra girth using flexy plastic...I've seen some "how to's" online for fatbikerz...