In order to get the slide out without using a forklift will require that you use cribbing. Cribbing is nothing more than 4x4 or 6x6 piled high enough to support the slide as you move it out. You didn't say whether it was cable actuated, pinion gear and linear or hydraulic. Since you said one slide, it is most likely cable. You will have to disconnect the cables, remove the interior molding then push (actually drag from the outside) the slide out onto the cribbing.
You can probably rent cribbing from a equipment rental company or a rigger company. Once out then you can work on the slide one section at a time. Push the slide forward so about 1/4 hangs off the cribbing, replace the floor. Place a 4x4 under this new floor area and jack it up to support the front as you remove cribbing under the next 1/4. Jack up the front a little and put cribbing back under the 2nd 1/4 you just finished. Work your way back along the whole bottom.
Good luck.
