m0useanswered grow question 3 years ago you could get a nice 1000w led that would fit in a 4x4, but the purchase cost is going to be high.
save 800W in the end. Also dimmers aren't bad from what I know, I don't fully understand why having one is out of the question.
something like this could blast it away. ignore the c02 part of its name, stupid marketing.
https://photontek-lighting.com/shop/xt-1000w-co2-pro-led/
Good Luck!