I used the Ultimate Petliner as a template.
Placed it over the plywood and traced around it with a pencil. I cut it a little smaller to allow for clearance for the carpet and some wiggle room. After cutting the wood, I chamfered the edge that meets the door sill by routing the top edge with a 45 degree bit. Rounded out all the top edges with a belt sander. The carpet is attached using 3M contact cement and stapled on the bottom.
Using longer bolts, I anchored the plywood to the deck (directly over the factory carpet) at the 4 factory tie-down points. I ended up removing the D ring tie downs from 3 of the points except for the rear driver's location and replaced them with flat washers. I also put spacers (3/8"-1/2" IIRC) between the plywood and the body at the front location to level out the board.
The ARB slide tray is secured to the plywood with 5/16-18 bolts and 5/16-18 T-Nuts on the underside.
The ARB fridge is one of my favorite accessories.