Yeah I think next year Im going to use the 28" pots and ditch the 5 gallon buckets. Ive seen people pull off plants in a 5 gallon bucket but it didnt work out too well for me. Ill probably move the secondary plants into the yard or a raised bed.
re: using 5 gallon buckets. I have used 5 gallon buckets and 14" flower pots in the past, largely on an experimental basis, and didn't have much luck. The 14" pots did better than the 5 gallon buckets, but it was my experience that the pots got too hot in our abundant sunshine. There was no comparison between my soil based tobacco and the flower pot based tobacco. Since then, I have opened up more garden space and discontinued the buckets/flower pots. Less lawn mowing, more tobacco!