Dual discs for the 06 and up Dynas have been in high demand and Harley has yet to answer the call, except on the 08 and up FXDF.
A guy named Howard Messner , has done this conversion on a Street Bob successfully and done it right. He basically accomplished this by using the sliders from a VROD, which has 49mm tubes. He had to do some machine work and modify the damper and other internals.
The fact you want to do this on a Wide Glide complicates your task. The Fat Bob sliders are not a direct swap on your application. You have a 1" axle, where the Fat Bobs have a 25mm axle. This would mean the sliders, new axles, and new bearings. Then you have to deal with the calipers. The Fat Bob uses a different left side caliper, so you would have to purchase both, plus the lines, plus a new master cylinder.
Good luck and happy pocket digging. This is gonna get expensive.