So, snooping around in folders, I found that in the path for Mac /Applications/Planeshift/art/skins/base/client_base.zip/maps/ there are some folders named "cloth", "leather", "parchment", and "vellum", which are all working backgrounds for in game maps. Right now, though, the only one available is "leather", but renaming folders and repacking I'm able to use the others. How about properly implementing this so maps actually have more variety, since we can't use more than 200 elements in them?
Proof of my find: