When the bounce really matters is when the box is loaded with contents. The downward motion of the box plus contents puts max strain on your crossbars.
Take this for what it’s worth from a guy who has had the same Yakima Skybox on a 2013-2019-now 2021 Outback. The box look real purty centered exactly on the crossbars, but that is where you will get maximum flex. It’s much stronger to have the box as far left or right, driver or passenger side, so that one side of the box is weighing on the strongest part of the crossbars, the anchor spot.
I like to have my box as far to the passenger side as possible for a few reasons. ONE the weight of the box plus contents on the passenger side is balanced somewhat by my 250 lbs on the drivers side when I’m in the car by myself. TWO and even better, the box shoved to the passenger side leaves much more available crossbar for other things like strapping say, a pole saw, or a tent, on the drivers side of the bars. And THREE now this may not apply to the Ascent, but on my Outback, if I have the box centered, I need a stool to access either side of the box. With it shoved to the passenger side, I can access most contents of the box flatfooted on the passenger side. Only needing a stool to access stuff that has drifted to the drivers side of the box.
Anyway, that’s my experience hope you enjoy your Yakima. You may know already, but you can change your locks to be the same as other Yakima products like Bike racks, etc so one key will service both. REI is one good source for Yakima stuff.
