A member here converted his SRW to a dually from a donor truck & it came out great. Here is the link to his pics ---> Ford Truck Enthusiasts Forums - Sheldon Plankton's Album: Dually Conversion

Sadly he fell of the grid and hasn't been on here for almost two years. Him and I went to BTS together to get our trannys built. He also has a big RV.

Not sure about the kit you posted above, haven't heard anything about it.

As a fellow RV'r I came from a single wheel Superduty to my dually & you are correct, the stability is amazing in comparison.
I do know a guy in Pa who wants to convert his dually into a single wheel truck. If your up for a road trip you may be able to work out a swap.