I’m not using XFCE but can recommend something of a mixture. You can make that command into a script file. Create an empty file on your home folder and name it screen.sh or whatever you want. Put your command in it like this and save.
As @stargazer shared from Arch Wiki, you should be able to directly add the script file it seems. Add a new autostart program and choose .screen.sh from file manager. Should be fine I guess.
No problem, glad you solved your issue.
I guess xiccd is not needed unless you’re a photographer. Though xfsettingsd seems apply different XFCE config files at once, by disabling it you may need some things to start manually.