I decided to use the free week to have a peek into FFXI again.
Downloaded windower4, edited my resolution in and now have the following problem:
The window is at the right size, filling out most of the screen.
The actual game image is too small though making it a painful gaming experience.
Screenshot:

Due to this issue the windower command line and plugins like distance are outside of the visible part of the screen.
Thanks for any help provided!
EDIT:
observation: FFXIconfig seems to reset itself constantly, maybe that's the issue.