S.D. Codified Laws § 50-11-27
Any aircraft of any resident of another state, and any nonresident person, having complied with the registration requirements of that state, may be operated or operate within this state for a period of not more than ninety days in any one year without complying with this chapter if the aircraft or person is not engaged in any intrastate commercial activity within this state, and that under the laws of the state of the person's residence, like exemptions and privileges are granted to aircraft owned by residents of this state and resident persons of this state duly registered under the laws of this state. A nonresident under this section is a person who has not resided within this state for a period of ninety days. Failure to register after ninety days is a Class 1 misdemeanor.
SDCL 50-11-27