Perhaps it's worth considering succinct data structures (https://en.wikipedia.org/wiki/Succinct_data_structure), e.g.:

- BitMagic: http://bitmagic.io/, https://github.com/tlk00/BitMagic

- Succinct Data Structure Library 2.0: https://github.com/simongog/sdsl-lite, https://github.com/simongog/sdsl-lite/wiki/Literature