We used to grow about 200 so that we had plenty to sell at boot fairs, when the autumn came after the first frost I would lift 2/3 plants of each variety ,get most but not all soil off. Then I used to pack them under the staging of my greenhouse with bubble film between them and the glass. The greenhouse was kept just frost free but nnot heated for growing. In the spring the remaining soil would drop off and I could slit the tubers up ready for replanting. I think by leaving some soil on it helped stop the tubers from shrinking.
