It is touching that you have such dedication to an outmoded rendering tool.
The fundamental drawback in LightWorks is adjusting lighting, because the basic engine as implemented in Archicad can do almost any surface well.
Before investing, review the archive surfaces [load settings from archive] that are supplied with Archicad but not made into materials yet.
Your issue in high resolution rendering is not the texture images, but slow production of larger images. SLOW. KRIKEY!
Arroway, Dosch, or whatever, are investments that will do you well once you move on to a real rendering application, even if you reduce them to 1000 pixel files for use in LightWorks.
Dwight Atkinson