yeah rabbid-chop is right, those aggressive looking bolt on flares are for wider muddies. Probably for 12.5" tyres on a wider offset rim.
$430 for a pair is still pretty decent coin to be lashing out and you'd expect decent quality and fitment at that price - again, I'd shoot the manufacturer / supplier an email to get a bit more information. You can make the comparison between the genuine and aftermarket flares if you can get your hands on a shop drawing of the Thai after markets....
For all we know they could come out of the same factory as the genuine flares and the savings come from Nissan (the middle man) being cut out (rightly so, the rip off bastards!)
Nothing ventured, nothing gained - plastic's can easily be tweaked as well, providing the fixing locations are relatively close to where they need to be.
For any future trips, the only other suggestion I have is remove the front mudflaps when you arrive, you don't need them on tracks - Should be a winner