S.D. Codified Laws § 55-15-3
If there is no trustee of the trust other than an interested trustee, the interested trustee or, if two or more persons are acting as trustee and are interested trustees, a majority of such interested trustees, may, in its sole discretion and without the approval of any court, take such action as provided in § 55-15-2 so long as the trustee appoints a disinterested person who, in its sole discretion but acting in a fiduciary capacity, determines for the trustee (i) the percentage to be used to calculate the unitrust amount, (ii) the method to be used in determining the fair market value of the trust, and (iii) which assets, if any, are to be excluded in determining the unitrust amount; and complies with all of the provisions of subdivisions (1) to (4), inclusive, of § 55-15-2.
SDCL 55-15-3