This may not be what the original poster is looking for, but may be what others are looking for. I wanted to eleminate the braided hoses on my rims because they were a pain to polish around and I didn't like the looks of them. I had looked at dually valves and thought they were outrageously priced for what they are.
When I put my new rear tires on, I just bought a long metal valve stem for the inner dual from the tire store. He had them from 3" to 12" lengths. He charged me $10.00 each, which I thought was still expensive. I've found them on line, including here patchboy: TR #510, 5 1/2" Nickel Plated 90 degreeTruck Tire Valve, 1 Valve
for less. The metal stem on the outer dual I turned and change the bend a little. They're very soft and easy to bend where you want them.
On the 22.5 alloy rims, they make a rubber grommet that fits in one of the wheel holes that supports the long inner stem from dangling. I still didn't like that look. I made a support out of a thin sheet of aluminum that attached over the wheel studs between the duals. Here is the pattern:
Now my wheels look like this with the long valve stems: