Is there a way to search for dates with values and empty dates in Searchkick?

Question

I'm just wondering if something like the following is possible?

@things = Thing.search("*", {where: build_where_clase})

def build_where_clase
  filter_params = {}
  filtered_params[:due_date] = Time.current.beginning_of_month..Time.current.end_of_month
  filtered_params[:or] = [{due_date: nil}]
  filtered_params
end