In any case you'll have to move/spin the plants to get full coverage and you want some side lighting so maybe lower down by, but not next to the plants. I would try to cast the light from the top down at the plants at a 45 deg angle, that way all you have to do is rotate to stay even... yes they will start to lean if you don't rotate them, but 2 or 3 rotations per day and they'll stay straight up.
There are also automatic plant spinners to be had out there for a price....