Don't the african masks have a necessary dormant period though? Have you ever tried microsorum thailandicum in this sort of setup? It's got incredibly iridescent blue leaves if you're not familiar.
http://www.asiaticanursery.com/_ccLib/image/plants/DETA-140.jpg
http://farm4.static.flickr.com/3217/3156864599_e0fb382990.jpg?v=0
http://www.asiaticanursery.com/_ccLib/image/plants/DETA-140.jpg
http://farm4.static.flickr.com/3217/3156864599_e0fb382990.jpg?v=0