Does the internal volume of the evaporator is kept constant?, if not; I think the evaporator pressure increases for a given refrigerant charge. Hence, you should reduce the refrigerant charge and increases the capillary tube length.
You can use Refrigeration and Air Conditioning 2nd Ed. - W. Stoecker, J. Jones WW, to calculate the new length of the capillary tube.
You can use our Cloud e-Tools available at www.refriglab.com to size your evaporator coils with tube OD from 16mm to 4mm and capillary tubes separately. The use of smaller tube evaporator coil helps reduce the refrigerant charge quantity, and enhance the unit compactness.