You could always stand them on a box or something so they're under the skylight, but I don't think you'll get 6 of them under a square foot of light, not once they've grown a bit at any rate.
An 8" plant won't be root bound in a gallon pot. I grow mine to 3 foot or so and they stay in 4 litre (just short of a gallon) pots for the last 10 weeks of their life with no problem.
You don't need big pots to grow big plants, you just need to feed and water when the plant needs it. The hard part is knowing when the plant needs it.
I wish you all the best, but I would suggest maybe growing them under the skylight for a week or so, then pick out the best 2, maybe 3 plants and try to make something of them, rather than cramming 6 under there.