I hate to sound so negative. I have been growing with cobs for 2+ years and sold over 500 lights since January. For that height I would not use cobs. Most people underestimate their power first off, secondly cobs deliver so much raw power and it all comes from a very small area. Clu-048 cobs are only 28mm with higher par than a standard 300 watt led panel which are spaced over a larger area. Going with 100 watts is like having a 600 watt LED panel and again from a smaller area. If I was you I would get some e-26 screw in bulbs, cut the diffuser off and run 4 in there. Total of 50 watts and spread out over multiple smaller leds. Efficiency is close enough and the cost is much lower. If you do decide to go cobs I wouldn't think the plants would last long before they were burnt up.