looking at this picture
https://www.rollitup.org/attachments/img_1236-jpg.3840837/ i was imagining how much better it would be if the plastic wrap around the cubes were removed. there'd be a whole lot more room for roots to grow.
not saying that's what you should do, i know you already said you over vegged them. but it got me thinking of a system.
Imagine your table just the way you have it. you line up those same size rockwool cubes, say 12 by 6 spaced out evenly.
then you take a sheet of black lightproof plastic and make holes in it 12 by 6 that correspond to the rockwool cubes.
then you lay the sheet over the rockwool cubes and have your seedling/clones grow through the holes.
then you can remove the plastic around each cube because you have the black plastic sheet covering the roots.
you could then run a nutrient solution continuously from a return reservoir or flood and drain it.
the roots would be massive and the trees a lot bigger.
just something that came to mind is all.