In addition to other investments permitted under this chapter, mutual aid associations may invest in funeral supply inventories, consisting of caskets, suits, robes, dresses, and embalming supplies, and funeral equipment, consisting of automobiles, hearses, ambulances, funeral cars, and other motor vehicle equipment, to the extent reasonably necessary to the full performance by the association of its outstanding contracts and policies. Such funeral supply inventories shall not exceed 25 percent of the association’s assets.