Instead of using documents to add data to an index you can use Hashes and Arrays. The only real benefits of using a Document over a Hash are pretty printing and the boost attribute. You can add the boost attribute to Hashes and arrays using the BoostMixin. For example;

class Hash
  include BoostMixin
end

class Array
  include BoostMixin
end

class String
  include BoostMixin
end