A 5 gal. pot would be considered the minimum size. I don't pinch/prune any of mine, but I can't recall ever moving one with fruit on it.

For planting vegetables/fruits in containers, I cannot recommend Smart Pots strongly enough. These fabric cylinders have served me well for 10 years on a hot roof deck. They're showing signs of wear now but they've definitely been worth it. Cooler, better for roots, durable, many sizes

Get some Smart Pots fabric plant containers (at least 5 gallon)....tomatoes love them if you don't have an garden plot. Also fertilize with Epsom salts and fish emulsion and you can also spray the plants with Epsom salts mixture:

How to apply Epsom salts

When planting tomatoes: add 1 tablespoon to planting hole and work into the soil before planting tomato seedlings.

Early to mid-season: using a tank sprayer, combine salts in a gallon of water. Use 2 tablespoons salts per gallon when applying once a month; 1 tablespoon per gallon if you apply more than once a month. Early and mid-season applications encourage plant growth and prevent blossom end rot.

Late in the season: apply as a spray to increase fruit yield and keep plants green and healthy.

As a side dressing: work in 1 tablespoon per 1 foot of plant height into the soil around the base of the plant every six weeks. Granular application impacts the plant more slowly than foliar application, but produces the same benefits. Be advised that as much as 49% of granular applications have been recorded to leach out of the soil before they’re absorbed by the plant.
Good luck!!

I took your advice and ordered a bunch of ten gallon smart pots and will attempt to repot this weekend. I'm pretty scared about repotting plants with fruit on them, wish me luck....

Please don't use Epsom salts unless you know your soil/potting mix is deficient in magnesium. Excess magnesium can actually make blossom end rot worse. Blossom end rot has nothing to do with magnesium deficiency.

There are many Extension articles cautioning about Epsom salts for blossom end rot, here is one:

https://www.ag.ndsu.edu/yardan...

Okay so I ran out of soil to repot all of them last night, but here is one of them repotted into the ten gallon Smart Pot! I will repot the rest of them in a few days when Ive had a chance to pick up some more soil.

Someone suggested to me that I should trim off all of the existing fruit and the flowers to allow the plant to focus its energy on being ripped out of its home and into a new one, and not exhaust itself. Do you guys agree? I trimmed off several of the lower branches and buried them, so I imagine those will root eventually, right?