S.D. Codified Laws § 44-8-8
The recording of any mortgage or trust deed affecting real property which was otherwise entitled to be recorded and which prior to January 1, 1992, was copied into the proper book of records kept in the office of any register of deeds and which has been properly indexed in that office, against the real property affected by such instrument shall be deemed to impart sufficient notice of such instrument and its contents to subsequent purchasers, encumbrancers, or creditors, notwithstanding that such mortgage contains one or more provisions which are prohibited by § 44-8-7, and the act of any register of deeds in copying any such mortgage or trust deed into a proper book of records kept in his office and in properly indexing the same in his office against the real property affected by such instrument, is hereby legalized, cured, and declared valid; but nothing herein contained shall affect the rights of purchasers, encumbrancers, or holders of a valid lien by court proceedings who became such in good faith prior to January 1, 1992, provided further that this section shall not legalize any of the prohibited provisions contained in any such mortgage.
If any person has any vested right in any real property by reason of any omission referred to in this section, and if no action or proceeding to enforce such right was commenced prior to July 1, 1993, such right shall be forever barred. No action or proceeding brought involving real property shall be of any force or effect, or maintainable in any court of this state, unless prior to July 1, 1993, there was recorded in the office of the register of deeds of the county in which the real property affected is situated, a notice of the pendency of such action, in accordance with chapter 15-10.
SDCL 44-8-8