Risse Racing has added a Fat Bike compatible version of their Trixie dual crown fork.
Travel is brought down to 100mm travel, which provides clearance for up to a 3.8 tire with about a quarterinch to spare between stanchions. It uses an air set up with oil damping. Internal spacers allow you to change travel, so you could move the fork to other bikes with different wheel sizes. This one actually could double as a 29er fork. Front hub spacing is 120mm, which works with any 20mm hub natively or with their 5mm spacers (one per side) for 110mm hubs.
Fork weight is about 6.5lbs and runs $595.