https://ibb.co/wJdjLm8
I've spent so many years now with separate chat windows that I can't even remember how confusing it was to only have one. But I used the /viewport command to have a 1440x900 area and used the rest for the visible UI elements. Spellgems window is misplaced in this screenshot, and the buffs window is in the top right (I didn't have any active buffs at that time)
saved the ini files as UI_NEWCHAR_project1999.ini and NEWCHAR_project1999.ini. Now just have to copy, rename, and replace the files created by new characters and all of my settings are good to go.