basicly all i would use them just to mnake them stiffer, so i have a better onroad drive, then if i come to do some ofroading, i can adjust them and soften them for the trail
In that capacity, I'd say yes, the air shocks should work for what you intend to do with them, in theory. (Rancho has done this with the RS series. They even provide a compressor and manual valves to bleed them from driver's seat.)
Do note, that the spring holds the weight of the vehicle at a certain static height. If the air shock has 0psi, the shock is just sitting at whatever length the coil makes it. Adding psi to the shock, at some point, the shock will start to increase the coil. That's what adding air does.
Think of it like a balloon. If the balloon has no air in it, it's flat and winkled. By adding some air, it will still be flat but not winkled. Then adding more air, the balloon will get out of shape by expanding. Same with the air shock. At some point, the psi will expand it to extend the coil from it's static height.