In the last few days I have been working on the last missing feature of the Ground Polygon Wizard of ModelConverterX, the option to add night and seasonal textures from the wizard. This work is not completely done yet, but the part that generates the actual code is done. I just need to finish the graphical user interface and do some more testing. So hopefully I can release this feature in a couple of days. On the right is a small preview of how the user interface will probably look. For each material you can specify with a checkbox if it needs a night texture or seasonal textures as well. Just like you specify the layer and visibility range.