Yes ActiveRecord, you will bow to me.

hack.rb

scope = RealModel.where(name: 'foo')
threads = []
dbs.each do |db|
  threads << Thread.new do
    dynamic_class_name = "TempModel#{Thread.current.object_id}"
    dynamic_class = Object.const_set(dynamic_class_name, Class.new(query_model))
    begin
      con = retrieve_connection(db, resolver)
      dynamic_class.establish_connection(con)
      local_scope = dynamic_class.all.merge(scope)
      results[db] = local_scope.to_a.each(&:readonly!)
    ensure
      dynamic_class.connection_pool.release_connection
    end
  end
end