Mad respect for your growing skills and technical knowledge bro but I gotta call you out on that yield claim.
I don't know what varieties some of you guys in other parts of the world are growing, but here where I am (think Humbolt Cali) the strains people are wanting to smoke on do not produce yields like that. And most are leggy, stretch, unruly girls that would surely not perform in such a low ceiling height situation.
Would love to see what you can do with a cut of some of the "clone only" Cali goodness.
But who knows, maybe a SOG of Big Bud is just what his market is after
Hmm! 500g with 330w or 1000 per HLG-600 (650w) should be doable. 2x 5' are 10sft so 50g per sft, I pull usually 50-60g depending on strain. Imagine a 4x 5' area covered with 650w of LED strips. It's the same like two of the 2x 5' trays stacked. And with a see of green, 2-7 days veg, 20-25 plants per tray and a coco dtw system you could easily pull more out of this area.
My area has exactly 2,5 x 4' and I pull regulary 450-550g out of this area and this was in my own low fertilized organic soil and cheap tomato fertilizer, molasses and kelp extract. No fance grow shop stuff.
I rebuild the cab currently and switch to a coco dtw system with up to 10pcs 6l pots and my light pulls ~335w out of the wall. The two pureUV bulbs add only 1,8μMol/s/m² per bulb so its calculated without these bulbs. They run anyway only for 1h per day. So its 48w : 12 =4w more if I calculate them in.
With coco in a DTW setup I hope to yield even more. I've seen 4 plants grown in 5l pots coco dtw, 250w F-strips, 3 weeks veg and finished with ø80g per plant, +320g out of a fuckin' 2x 2' area.
SOG and a high yielding strain like Chronic(serious seeds), DutchDragon(Paradise seeds) or NYC-diesel(soma seeds).. Unbeatable! SOG is a bit more work because you need at least 25 healthy cuttings per squaremeter but its for sure the most productive grow style. When you use only one strain you get a nice and even canopy every time without training. With meanlining you can get similar results but it takes usually up to 45-60 days until you have 8 equal branches.
With a SOG most of the time only one week or less is needed. Only very slow growing indika's like Bubba'sGift from HSO need up to 2 weeks to finish with 20-24" height. SSH cuttings I've directly put under 12/12h, no veg and they have finished with ~28-32", easily 600g/m² with 25 plants per 600w HPS bulb. The term lollipopping is from such cuttings cause the lowest third of green is normally removed and the shape exactly look like a lolli. Only a huge single cola of 14-20" length and no twigs
Believe me, thats easily doable! Even more! If you don't reach such results I'm willing to help. You have anyway planned to create a new light, what's when we change your grow style too? You don't need an extra mother tent. We take the cuttings within the first 7-21 day after transplanting and we take only the lowest shoots we would anyway lollipop within the next weeks. There are only very little flowering hormones at this moment and even if you see a few flowers already you can still cut and root them. And until the other plants finish you can root the new clones. When they have rooted faster which is usually the case put them into small 3x 3x 4" pots for another two weeks and hand water them. The better they have rooted-in the faster you can switch to flowering. Usually you get at least two cuttings per plant which means you have two times more than needed for the next run. This makes sure you have always enough cuttings and can choose only the best ones. So you need only a selfmade cloner and a small area big enough for the cloner and 25pcs 3x 3" pots. Maybe 20x 40" with a 50-75w strip light and your regular flowering area. If you use a tent the clone area could run without. An old cupboard would be enough for clones and cloner.
And it depends not only on the location and seeds. HSO's BlueDream or Trainwreck are known to yield very good. Most US peeps use a longer veg period but thats not that efficient. Even if you need only half as much watts in veg it sums up and in the end you need 30-40% more energy for the same yield. Here in europe we pay +30€ct, that's 35US cents so its one of the main reason why we are focussed on the SOG style. Its also the fastest grow style and 6 runs per year are possible with a 50-55 day strain. You pull much more per year out of the same area this way. You can yield the same with a scrogg but not in the same time.