This is the camper platform I made for our suburban:
It's secured to the front latch points (latch bars removed) of the 3rd row seats with a M12-1.5 bolt (possibly a -1.75, I forget the exact thread pitch).
To make a cargo slide, the easiest way is probably to just get a sheet of 3/4 ply and cut it in half so you have 2 4'x4' pieces- one for the base and one for the slide. A 4' platform will give about 1" of clearance on either side. Then buy some drawer slides and the appropriate mounting hardware.
If you don't want to remove the latches you could potentially secure it with hose clamps around the latch bars, u-bolts, or even some ratchet straps. The M12 bolts I showed above is probably the easiest option, since once you remove the latch bars and line your holes up, you don't have to fiddle around with a blind install.
As for mounting the drawer slides to the base sheet, I would use a combination of 3/4" machine screws and T-nuts, provided you have enough clearance within the slides for the screw heads. You could also just screw in a bunch of 3/4" wood screws, which would probably be fine, but is not ideal from a structural perspective.
