This works GREAT!
Some helpful information below.
Here is a few pics of a similar system using an York style AC pump for a compressor on a ford. The compressor on a duece will handle a lot more air than this.
AIR-UP
With this setup, I was able to air 4 35 x 12.50 tires from 0 psi to 30 psi at the same time in less than 5 minutes.
AIR-DOWN
If you put a valve on your fill, you can disconnect it from the air source, open it and air down in the same manner.
EQUALIZATION
If the schraders are worn, dirty, etc, they will fill at different rates, if you have them hooked together, and let them sit (blocked from airsource with valve) the tires will equalize until the air is the same in all.
With this being said, yes the schrader is the limitation, but the compressor will most likely have much more flow than even 8 schrader valves.
This system is proven to work very well if you take the time to build one. I might suggest using the smaller air hose as it will store easier. The system I made was using std 3/8 air hose.