So it seems that either I have no understanding of how the Nexus works.

Or it works differently than described in the manual. Maybe they are assuming the level file will be the biggest file? However, since my levels use meshes rather than level blocks, the levels are small, while textures and other linked files are much bigger.

Do i need to add up the total size of all the files that will be loaded into a level and use that as the nexus?

Sorry for all the ranting and open questions, I just have no real understanding of how this works. So far I've gotten around this by setting the nexus as high as possible (500mb) but it would be nice to be able to set it to a lower level and save memory if possible.

Rather than going with a trial and error approach, I thought it would be best to understand how it works first.