Dropping those bucket heights/sizes doesn't seem so crazy now, does it?
I have a full 3.5 vertical feet of plant growth space in the front of the tent and 2.5 in the back where that huge ass filter is. It is a moot point if you are using a SCROG, but I use trellis line attached with bungie cords around the corner frame of the tent that allows me to slide it up and down as needed. It gives me the ability to pull them down or tuck them a little as needed. Also provides support for heavy branches (which I hadn't needed until this run.
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D - how tall is your closet from floor to ceiling? There IS a"32x32"x84" if you have a full 8 feet and think the 115 bucks is less than any construction materials. That top shelf has to go either way, though. And that high, I would mount your panel and filter to hooks in the framing of the ceiling even if it meant patching holes in the tent. You may want to stick with the closet itself. I went with a tent because it was cheaper and easier than modifying my closet.