I've completely redone the Snowflake Mountain entrance and the Dino Domain exit, as well as the tunnel leading to the bridges. I'm not going to bother trying to sort the textures from within sketchup as it is highly impractical. I'll leave it till last, when I export it to 3DS Max.
http://s17.postimg.org/t5wkxl68t/Sequence_Area3.png
No idea how I'll group it into chunks, but I guess that should be easy enough as long as I continue designing the map around that grid...