My answer may not be suitable for the fuzzy sliding mode control but in general the most trivial solution is decreasing the gains of the controller. Secondly for very slow process you can either modify the reference signal accordingly or change the operation of the system from open loop to closed loop rather slowly but continuously.
Actually I was working with HOSMC on the Underground Coal Gasification (UCG) process, and I got rid of the saturation of the actuators and overshoot by the above methods. By the fuzzy sliding mode seems to be an interesting thing, can you share a review paper with me in this context