I grow taller plants with 1K's. 6 footers + I have no problems with lighting! You don't "have" to light the lower sections. They get their fair share of feeding and energy from the rest of the plant doing it's job. Some lighting is a plus and it should be doing fine from the 1K.
Paint the walls around the area with flat white ceiling paint.
Look at the plant from the side. Now imagine a cone shape pointing up and going 1/3 of the plants height. You should be "lollypopping" that away. The lowest branch's never really work anyway, and the shaded interior produces the weak/draining "sucker" like buds anyway. They detract from the others, even the mains. Trim this stuff away and the remaining "lowers" do just fine!
You should consider a stepped or staggered harvest. You harvest the ripe mains to the point that the buds look like they need some more time (unripe). You let that go for a week to 2 weeks - till they look ripe. Harvest again. BTW, it was found some time ago that those lower buds allowed to ripen. Are more potent then their big sisters from above them...
Understand?