as tmsn said, the logo top platform really is narrow, and you probably wont be happy with it if you plan to strap stuff on that part of a rack.
also, the tubus rack stays have swiveable mounting points on the actual rack area, so its easy to angle them inwards or outwards to the mounting points on a bike, and then of course do a bit of bending if need be to align the end point with the hole in it. This shouldnt be a big deal to do.
just to add, most of us have used aluminum racks forever, so depending on what sort of travelling you intend to do, or simply put, not putting an outrageous amount of weight on your rear rack, a well made aluminum rack works fine---Ive used alu ones for decades AND I do own tubus racks, so Im not being biased and base my opinion on lots of personal experience.
but all that said, the wider top of the Cargo is nice looking, I just preferred to get the lower railed Logo, and Im glad I did, I like having the weight lower.
In the meantime, the idea to add on some sort of easy to add structure to your existing rack would at least make it flat, and easier to put what you want on it--which is what btw--a tent? Even some sections of plastic at intervals could flatten the curve (hey, had to put in a pandemic reference-good luck all you Americans btw for the next month or so) and not be heavy or bulky.
maybe check out google images for your bike + tubus cargo searches, maybe you could find some closeups from above of the mounting