Since I searched a lot and found little info, I thought I would share my findings in searching for a cargo/ski box for my 4runner that is compatible with the 2019 TRD-Pro Rack.
My criteria started out as a box that fits my longest skis, (194s) and and a few snowboards (so it needed to be wide) and works with the tubular TRD-Pro rack... This proved to be more difficult than I thought....
First off, any of the boxes with recessed channels for the cross-bars is going to fit poorly, if it all. NO amount of shifting crossbars would allow a super low profile INNO box fit. The other big hurdle we hit, was most boxes couldn't shift far enough forward to open the hatch. Which was something I found unacceptable. So I started looking for flat bottomed boxes, Thule has some, and one that is long enough for my big pow skis...
At the shop (rackNroad in Seattle) the guys helped trial fit a few boxes. Very few wouldn't crash into the rear tubular bars....After the 4th or 5th box, we eventually found one that fit, a Thule Box. And due to a very upswept rear edge, it looked like it would fit with cross bars on the lower..
Here is the Thule Box mounted on crossbars on the top tube of the Rack:
And here she is nestled down on crossbars mounted on the lower tube, with a few mm to the rear lateral tubes, and fully open rear hatch. It over hangs a bit more than I would like in the front, but should be fine for now...
One thing that does annoy the heck out of me, is access to the key/lock. It is a tight fit as it lines up directly with the top tube of the rack. I'm trying to tell myself that the lock becoming hard to reach is a safety feature.... I'll see how annoying it gets when it is freezing cold and covered in snow..