The only way that would be sufficient is if you didn't care about plant count.
Realistically, 2lb's in a 2x2 area isn't realistic at all. Expert growers who have been doing this for years are barely hitting the GPW (gram per watt) mark under 1000w bulbs in a 4x4 area...
In my opinion, if plant count is not an issue, Sea of Green is best, like you mentioned, stuffing 4-6 per sq foot in 5" containers.
Lets use our imagination
If you ran 5 inch containers, filled with whatever medium, you could stuff 81 plants under a 1000w bulb in a 4x4 table, with room to spare. With little to no veg time, you could make the flip, and hope for an average of 14 grams per plant, using the lollipop method. Thats a 14 gram cola/nug when dried/cured...thats pretty big, but realistic.
14 grams x 81 plants = 1134 grams.. about 10% over 1GPW, which is a remarkable goal...and this allows you to utilize all the space with perfectly spaced nuggage...right??
kinda.
While an evenly spread canopy is KEY to reaching 1GPW, along with a ton of other variables, using a high number of small plants is a waste of height.
I believe, using 1 plant per sq foot, trained/topped/fimmed/supercropped (WHATEVER you have to do to get all the branches at a level height filling in the canopy) is best because it allows for a taller plant where the brightness of a big 1000w bulb can penetrate the lower buds.
Im rambling and high as shit... there are many ways to get the best use out of your light / efficiency..its just a matter of finding what works best for you...this comes with practice and learning your strain...some strains like to be vegged out and produce monster buds whereas some create the perfect lollipopped SoG.
/end
/bong hit
edit: 4 per sq foot vegged to 9 inches and you would run out of room. Each plant only has 25sq inches to grow into. (5 inches x 5 inches) .. I get fan leaves that are bigger then that