my solution was to split it into ~80 other runtimes, totalling ~8 GB, which allows poser to find 'em if they're in top level of Poser Pro 2012 Content folder.

my Poser Pro 2012 Content/Runtime (you add downloads to this if you want) is ~ 6 GB.

my Poser Pro 2012/Runtime, to which I only add python scripts, is ~1 GB.

hence if you added 45 GB to Poser Pro 2012/Runtime, it might fail. if you added 45 GB to Poser Pro 2012 Content/Runtime, it might also fail, but it should work.

I split 'em up based on old habits, where OS X would overwrite folders instead of merging them, but PhilC et al. wrote merging scripts to use when unzipping runtimes. also daz install manager merges 'em properly, but installs content for PP2012 in correct place (shared). that's another ~6 GB, so I only got approx. 21 GB in toto. one thing that never worked well for me was trying to add runtimes from other discs. poser would forget where they were. so I quit doing that. I dunno if it's a bug or a feature.