Looking them up, I see Early Girl is "tall" ("9 feet" and an F1 hybrid (not open pollinated). 9 feet?! wow.
http://en.wikipedia.org/wiki/Early_Girl
There are other varieties that I like better. I have had poor results with "early" tomatoes -- Stupice (stoo - pee - chay) was especially poor, plasticky and tasteless. Celebrity was a hybrid that did well for me and the taste was better, although not top tier like the Brandwines and the Oxhearts.
For containers I like Sweet 100, Sungold and Juliette (good for sun or oven drieds). I am growing some Green Zebras, cherry and Sungolds. The Sungold have done well. The Zebra has only 4 fruits on it and they have been slow to ripen (probably not enough sun in the spot where the container is).
I had about 40 plants last year but this year I am a guest farmer on a farm and they have 1000s so I am doing filet beans and edamame. This is a shot from last year. None of these did as well as they would have in the right hands, some are small, many cracked, (and some on the picture are under ripe but I wanted a group shot...)
I guess the answer for Early Girls is to trellis them and let them get tall. The Romas I grew stayed under 4 feet and put on a lot of fruit which bulked up quickly right at the end (around 75 days).
Good luck and Enjoy!