All the methods I know of( except mine, of course) require either turning a
face plate grooved to match the bowl lip or turning an extra amount on the
bottom to match a chuck. What I found in Wood Magazine # 45, Sep 91, p.
84 and stupidly listed in their on-line index as being for plates is this:

I turned one disc to the max diameter my lathe would take. Then turned a
second set of discs, same diameter but different size holes at the center,
padded the hole insides with rubber. Glued a piece of scrap wood to the
bowl bottom, fastened that to a face plate, turned the outside and inside
and finished them. Removed the face plate,then put the bowl on my solid
disc, picked the second disc of appropriate diameter and fastened it with
matching bolts to the base disc, turned away the scrap wood and finished the
bottom. Just finished two today and it works like a charm. If you can find
that wood article, you should read it first. There are probably more
details than I am giving here.

Bob Moody