I have had to deal with a similar situaton. Two suggestions:
Parallelize the import. I know you can't use Data Pump parallelism, but you can run multiple Data Pump sessions. Perhaps one session per schema, or (if you can work out the dependencies) multiple sessions within a schema.
Tune the import! There is a huge amount you can do. I have found the biggest benefits come from setting constraints to enable-novalidate before the export; make all the indexes nologging; set pga_aggregate_target, _smm_max_size, and _pga_max_size to several G.
Hope this helps.
Oracle Certified Master DBA