In our desert days we used the "air spring" concept to good effect. It involves tapping the fork top plugs for a Schrader valve, then adding an "air cap" static charge to effectively boost the spring rate. In some cases the air WAS the spring, but you need a lot of faith in your fork seals for that. The oil volume inside the tube determines compression rate. As they compress, the volume decreases, the air-spring pressure goes up dramatically. This can be used as an "anti-bottoming aid". Understandably the oil volumes of the forks need to be determined, as well as the C.R., but you can easily do this with a "Ratio-Rite" graduated cup and a quart of ATF.
While the forks are off, and hopefully apart, you could tap a 4mm screw hole in the slider bottom to facilitate fork oil changes. A red fiber washer is adequate for sealing. Whilst running air assist, any fork seal leaks become readily apparent.
The advantages to air assist is that lighter springs can be used, then the spring-rate fine tuned through the air cap pressure. Internal C.R. can be set up to avoid bottoming. The only adverse effect I ever heard of was one hero managed to pop out the fork seals over a jump because he didn't use the snap ring to retain them. Using no springs leaves you at the mercy of your seal integrity, but reduces the unsprung weight, increasing suspension compliance.
The main drawback to air assisted springs was temperature related. The air spring "rate" changes with pressure, and if the forks were working really hard off road they would tend to stiffen up a bit as they heated up. For street & trail use, I doubt that would become a concern. - ACR -