The board of supervisors to whom the petition is addressed shall preside at the hearing provided for in section 358C.5 and shall continue the hearing in session, with adjournments from day to day, if necessary, until completed, without being required to give any further notice of the hearing. Proof of the residences and qualifications of the petitioners as registered voters shall be made by affidavit or otherwise as the board may direct. The board may consider the boundaries of a proposed district, whether the boundaries are described in the petition or otherwise, and for that purpose may alter and amend the petition and limit or change the boundaries of the proposed district as stated in the petition. The board shall adjust the boundaries of a proposed district as needed to exclude land that has no reasonable likelihood of benefit from inclusion in the proposed district. The boundaries of a proposed district shall not be changed to incorporate property not included in the original petition and published notice until the owner of the property is given notice of inclusion as on the original hearing. All persons in the proposed district shall have an opportunity to be heard regarding the location and boundaries of the proposed district and to make suggestions regarding the location and boundaries, and the board of supervisors, after hearing the statements, evidence, and suggestions made and offered at the hearing, shall approve or reject the petition. If the petition is approved, the board shall enter an order fixing and determining the limits and boundaries of the proposed district and whether or not all present and future property owners within the district have waived any objections to the annexation by a city if the district has issued obligations or bonds for public improvement and the city assumes those obligations, and, if the petition was requested under section 358C.3, subsection 1, directing that an election be held for the purpose of submitting to the registered voters owning land within the boundaries of the proposed district the question of organization and establishment of the proposed district as determined by the board of supervisors. The order shall fix a date for the election not more than sixty days after the date of the order. If the petition was requested under section 358C.3, subsection 2, the order shall fix a date for the organization of the district.