Do you happen to have any trellis netting to set in there to support your branches? It can help you keep the canopy down as well. I can’t lie though.. I’ve seen some plants get pretty close to these lights, and not sustain any bleaching of the buds. Of course the lights could have been dimmed to prevent it if it happens.
I always try to keep a minimum of 12″ from the light, but it doesn’t always work out like that growing multiple strains in one tent. That’s what got me into going with 1 big plant for my 4×4. There was another learning curve around that corner that I didn’t see coming though. The plant needs more feed than the usual, because there’s more plant to feed.