I always put a few tomatoes in containers, but as you say use my biggest nursery pots, somewhere between 30-40 gallons. They are large enough to allow a concrete wire tomato cage which is tied to a pergola that is over half of my main gardening area. Would do just as well to drive a post beside and twist tie the cage for support. I'm just too lazy to use anything other than the tomato cages, and am excited about the prospect of extending them to 7-8 feet tall this year. That should contain even my most vigorous plants.
Eclectic gardening style, drawing from 45 years of interest and experience. Mostly plant in raised beds and containers primarily using intensive gardening techniques.