Another aside to this discussion.
If one is using the average 4Runner for over landing use, the roof, while the car is driving is only recommended to take up to 165 lbs in load.
Now, I know that we go way beyond that. That most of the European Overlanding base vehicles are built in a more "purpose built" design for overlanding, etc.
The whole reason for this is the dynamic load of wind and other air resistance and the leverage like effect that the rack system applies to it.
I personally know Thule et al go through pretty outstanding testing of all of their systems. That go well beyond 165 pounds (some cars are limited further like no more that 100 or so) that is because of the forces experienced at 70-95mph on the interstate and you get passed by a long haul trucker doing 25 over whatever your doing creating the concussion that is imparted. And that happens what ten to twenty times an hour on some major thoroughfares on the way from, let's say Des Moines to Denver?
The argument I'm making here is why the Yakima tent is the way it is. They correctly sized up the Average American Overlander. (Whether they be a car camper or not)
Unlike Africa, or Utah, most Americans, have to drive to their place of expedition trekking. If I want to drive the BLM lands in Nevada, I have a 2,000 mile drive ahead of me before I do that.
If I just want to drive through Glacier National Park, I have 2,000 miles to go first.
I don't care how strong I think my vehicle is, if I were to put a Spare tire, 8-16 Gallons of water, a hi lift, extra gas or anything else like that on the roof of my truck, (or the top of a camper shell that's anchored with 4-6 extruded aluminum clamps to the composite steel and plastic bed of my truck) I'd have to be comfortable with the level of crazy I'd have to be.
Let's think about it.
50-80 lbs for the spare.
40 for the hi lift.
40-maybe 128 lbs of water.
Anywhere from 30-60 of more lbs of gas.
On the low end, that's 160lbs before any concept of a tent, or god forbid, an awning.
Many rigs I see are Trucks with shells, rack on top. That shell already is a proverbial sail. Tightened down with a few clamps.
If it isn't a truck it's a 4Runner or Xterra or the like with a roof rack. Either that roof rack is aftermarket, like Yakima. Or it's factory, with some cargo cage on it.
Now take 160lbs attach it to a 36-48 inch lever arm. Anchor that arm with two M5 screws and repeatedly hit it with 100mph blasts.
That's a crazy amount of dynamic force.
A kind of force that is not experienced by our compatriots in Australia or Africa because the OffRoading starts in their back yards. (Less so for Australia admittedly)
The shaking and jostling of weight while driving off road is a pronounced amount of force. No doubt.
My point is it's different than the types of forces imparted while highway driving.
Yakima was developing a tent for their racks, for their customers. Ones who drive long distances to experience their out of the way adventures. Using their knowledge of how vehicles handle regular highway forces