You need to recheck these pages, https://xubuntu.org/download/ and https://kubuntu.org/getkubuntu/. Both offer still offer LTS version. But unlike Ubuntu which has 5 years support (10 years if you subscribe to Ubuntu Pro), those distro only receive 3 years support.
You can just install Xfce on Ubuntu and still get 5 years LTS, right? The few GB size difference for having some unused software on your system shouldn't matter compared to the size of the blockchain.