It is simple if you think about it.
Remove packages you do not want and replace them with your own package/configs
There is nothing more to do.
And then you can still enjoy an up-to-date Calamares, bluetooth, printing and all the rest ArcoLinux provides but it becomes your personal iso.
How to create your own repo is explained here. How to create packages is explained in videos about PKGBUILD.
How to change the look of the xfce4-terminal and make a package
After watching this video you will understand the workflow behind creating your own look and feel.
You can add so many other things related to XFCE4.