I will agree with you Scott if you keep it within GVW. If you buff things up a bit such as frame plating, longfield axles, trussing axle housings as need, ect you can probably get a safe 1,000lbs over GVW. The problems will arise if you go over GVW much in the brakes, clutch or the auto transmission, wheel bearings, ect ect ect.
You can probably go 2,000lbs over GVW but man that is pushing it bad. The truck might do it and do it for awhile but eventually this extra weight will take it's toll on the truck in every way shape and form.
Yes I know people all over the world overload the Hilux and run it hard, still not something I recommend or suggest and it could ruin your trip.
I ran my Taco hard way over GVW, it was built up, a lot. In the end I could tell it was taking it's toll on the truck so I got rid of it before things began to fail. I had the biggest brakes you could put on it with out serious mods and I was eating up pads like it was nothing. My rear suspension was fully custom built to take the weight and that cost me some cash on top of the already expensive front suspension upgrades. Other then chewing up brake pads it held tough though for near 50,000 miles of Pan-Am running at 6,000lbs. So in my mind and world it can be done but it is not a good idea unless you are going to stay within GVW stated by Toyota. They are all fairly tuff trucks Toyota makes and I have proven it myself. I am just not a fan of overloading a truck and then running it hard. It defeats the purpose if you want to keep the truck reliable for long periods of time in harsh enviroments, IMHO.
Cheers