Forgot to mention,

The crawl space is likely not a good idea. Reson being, it'll be difficult to maintain and manuver around the plants, prone to mold and mildew AND far more likely to attract insects.

I'd agree on the attic temp wise. Attics can get VERY hot on warm days.

The claim I read was each plant needs 2.5 square feet and can grow to 6-7 feet tall(bushier if topped)