I have the on board compressor and controller so I can inflate and deflate the pressure. Sure makes it a lot easier. I inflate the bags to about 50 psi when traveling with the 5th wheel attached and deflate when unattached just to get better ride comfort. I have tried all sorts of air pressure settings while traveling with the trailer attached and found my settings this way. The reason that I have air bags is that they make the whole setup ride better. It has nothing ( for me anyway ) to do with leveling. Chucking is greatly reduced with the bags inflated. I also have the 5th Airborne pin box. Before I had these, the ride was terrible. I have the AirLift bags, compressor and controller. When I bought them, the cheapest place was J.C. Whitney. Installing the bags was easy but the compressor and in-cab controller took a bit of time. The newer wireless system, which I do not have, would be a lot easier.
I do not deflate the bags before I unhook.