When we bought the bike I had ordered a SW-motech steel-rack with Givi adapterkit to fit a givi top-box.
We had a trip planned, so I wanted to fit the top-box by that time, so that my girlfriend would have a backrest for the motorway sections.
As it turned out the steel-rack would not arrive in time, I had to look for an alternative.
I read somewhere that the hole pattern of the Crosstourer an AT rear carrier are the same.
Therefor I bought the Givi SRA aluminium rack for the Crosstourer.
Apparently the handles on the AT carrier are a bit larger causing the front corners of the rack to hit.
So, I ground and filed them of in a way that followed the line of the lashing-holes.
Normally (picture not a CT, but same principle):
Than I made 4 aluminium spacers on the lathe (14mm high) that allowed me to use the original bolts (you could alsow just use some thin rings stacked together).
With the rack there are some steel spacers that fit in the holes of the carrier, so you can't over tighten and brake the plastic carrier.
Now I could mount a Givi trekker outback topcase, which style quite suites the bike.
We did the 4 day trip with al our luggage in the box and in an additional drybag strapped to the top, worked a treat!
The quality of the givi case is very nice as well, only the aluminium does leave some residue on the drybag.
Givi is making an aluminium carrier as well, but that's not available over here at the moment.
Plus, because they will mount it differently, the box will be further back and more upright.
With the box sitting closer forward, it's quite comfortable for my rather small partner.
Just wanted to share.