mad Wow, amazing, that works!
Be aware for people trying to do the same: if you have used @{ url }
throughout your theme/template, you need to replace that with @{ :origUrl }
. If somebody would like to know how to setup a landing page with sections and stuff, let me know and I'll make a post on the forum here how I managed to do that. But for now: the sitemap.xml consist of exactly one entry, which is exactly what I want!
Oh, also: to refresh the sitemap, I had to visit my landingpage and after that refresh the sitemap.xml. I disabled the caching, because I suspect that that influences the generation of the sitemap. So: disabling caching (for just a bit), load the pages that you want to update, enabling caching again. Not sure if caching does something in regards to the sitemap.xml (I sure hope so), but this definitely worked for me.