Planting is very wide but short planter box or pots?

[choxie]

So my grow tent is tiny and is only 5 feet tall. Does anyone grow in a wide planter box or something where I can have a large total volume of dirt but not have it be too tall?

Also another random question about auto flowers. Would a single auto flower plant be able to utilize 2 100 watt lights or would it be better to use 2 plants?