Since your valve has (4) ports on it, basically one for each bag, then I would go ahead and utilize it. You can shop around to purchase a set of analog dual needle gauges, so basically you'll have a needle for each airbag, and you can moniter them accordingly. Typically we would install the gauge so that the left gauge relates to the leftside of the vehilce, and the right for the rightside. The needles are usually different colors so you can pick one color for the front bags, and the other for the rears.
You can also install a thrid analog gauge if you want to that has a single needle and use it to moniter tank pressure. It's not required but a nice option if you choose too.
There's also the option to install digital gauges as well that look sweet. They can be mounted in the cab just as well, and they only require wires running into the cab as opposed to airlines. The digital pressure sender would screw into your manifold and then the wire would attach to them and run into the cab.
Here's an example of how the some gauges look.
Dual needle, 200 PSI gauge, lights up.
Single needle, 200 PSI gauge, lights up.
Round digital pressure gauge, different bezel and display color options available
Rectangle digital pressure gauge, also read tank pressure, different bezel and display color options available
We can offer any of the gauge styles shown above if you're interested. If so just shoot us a PM or email and we can get more information to you. We can also supply you with airline and fittings if you choose to run the analog style gauges.
.