Tom, you don't need to get a chuck. Fred Holder has a book on holding wood, most are things (chucks) that you can make yourself. I turn bowls, large ones - my lath can turn up to 30" and I often do 24". Although I have several chucks I turn between centres; it's also possible to turn inside and out depending upon your lathe and the access it gives you to the blank. Many bowl turners use a tap and make wood face plates, then you can glue your bole foot with titebondII, do the inside and then part off your foot. Go on line to Wood Central and wood turning on-line. there are more articles that you would ever want to read; all about bowl turning and techniques.
I mention the websites because pen turning has little exposure on both.