I agree that for the vast majority of 4runner long weekend campers and day trip trail runners, this subject is a little over the top, and I can appreciate that. My family and I go out for a week at a time (5-7 days) at least 3 times per year, and at least 2 of those trips we go to areas where we don't see a gas station until our last day. With 3 kids and 2 adults, you can imagine how creative we need to get with packing, especially since we have to utilize the 3rd row on some of these trips. Interior space is at a real premium, and the rack is packed solid with the not so heavy (but often times space intensive) gear like tents, sleeping bags, clothing, etc. We've even gone to the lengths of vacuum sealing things like sleeping bags so we can combine them in one box. Now I've really cut back on the fuel I bring, but water is extremely important when we're out of cell coverage in the desert and need to be prepared for the worst case scenario.
We do take trails that test the limits of the 4runner's IFS, so being able to remove the rear sway bar is really appealing to me, but so is keeping the safety of my family on the road. I like the idea of that anti rock product, and the price really isn't horrible considering what we pay for suspension in general. I notice that in the picture they have the charcoal canister removed as well as the spare wheel frame cross member. I wonder if the idea behind the cross member removal is that the bar they provide would now be the lateral support you lose by cutting out said cross member. Either way, with that cross member removed, it really opens up the space under there, and could be a way to combine a water tank with something else. I'm over the idea of a fuel cell, as fuel jugs on the bumper are just as easy and much less complicated, but a water tank and perhaps an air tank/CO2 would fit nicely together, two things I'm not so keen with being inside the cab. And with the water on the driver's side and some buffering away from the exhaust pipe, maybe it'll stay cooler? Good find!