It's a fantastic-looking idea, Usman. However, I think it may not be quite applicable to the Phantom. First off, the tailgate on this vehicle in the picture is quite broad - almost the entire width of the rear - while the FJ has a MUCH narrower tailgate. Secondly, the tyre that's been fitted here is considerably smaller than the 42 inch Swampers on the Phantom. As it is, the tyre cover is taking up almost ALL the space in the rear of the Phantom's tub. I don't think a solution like this would be practicable - or even possible, for that matter - on the Phantom.
The rear tub of the beast isn't REALLY going to be used for carrying any serious luggage...and I'll be more than happy, if it's able to accommodate just the spare, the exhaust, the tool box, a couple of spare fuel cans, the hi-lift jack, and some assorted bric-a-brac (possibly, a compressor and a fridge/freezer). What with the tub being somewhat smaller than would be normally associated with a vehicle of this size...that's going to be challenging enough unto itself!