This kind of factor would be outside the scope of a traditional installation and there aren’t really any tips for it. I’m guessing that you just wouldn’t have to tape the seams on the cement board but it clearly wouldn’t damage. And I would probably thin-set the Kerdi board to the cement board but I’m not aware of any written instructions that may specify a technique or another. You might all the time verify with Schluter and see what they might advocate.
American Showcase Hardwood
If you plan to make use of a glue-down transition as we did, that is the time to install it. Second, the “cushioned” sheet vinyl must be removed before you’ll be able to set tile. Cushioned vinyl has a foam backing that makes it noticeably thicker and softer than normal vinyl flooring.