When a preliminary plat has been approved by the board, an election shall be held within the district within sixty days to approve or disapprove the levy of a tax of not more than one dollar per thousand dollars of assessed value on all the taxable property within the district and to choose candidates for the offices of trustees of the district. Notice of the election, including the time and place of holding the election, shall be given as provided in section 357D.4. The vote shall be by ballot which shall state clearly the proposition to be voted upon and any registered voter residing within the district at the time of the election may vote. It is not mandatory for the county commissioner of elections to conduct elections held pursuant to this chapter, but the elections shall be conducted in accordance with chapter 49 where not in conflict with this chapter. Judges shall be appointed to serve without pay by the board from among the registered voters of the district to be in charge of the election. The proposition is approved if sixty percent of those voting on the proposition vote in favor of it.