Five to 6 pounds. With some more tweaking up to 7 or 8 pounds. IMHO Lower the humidity a little, increase temps to 88 to 90, keep day and night temperature near the same (within 10 degrees max difference), increase CO2 to 2000 ppm, short frequent watering cycle, eliminate the fan blowing on the plants and use heat tubes (PVC pipes in the corners to blow cooler floor air that is higher in CO2 back up to above the plant canopy). Keep the light thermal out put as low as possible with strong cool air movement through the tubes and get the light as close as light thermal output will allow as long as they are high enough to evenly spraed the light over all the plants. As long as you have adequate calcium ppm the fan postion is not needed to strengthen the plants stems so it is really a debit. As is the fan will neccesitate that the humidity be as high as you suggest which in all actuallity just lowers transpiration. Doing away with the fan will allow for a slightly lower relative humidity and therefore will increase transpiration and respiration. It does very little good to supply supplemental CO2, high heat and good nutrient/water supply if you slow down the respiration with a high humidity. Once you get things running well lower your relative humidity just a small amount and see how much more nutrient water you go through. Lower t both the tempearture and the humidity for budding. Say 80 80 85 degrees and relative humidity of 40% and evem lower for the last tow eeks. Increased water uptake means increased tranpiration and respiration. Increased transpiration and respiration means more growth. However with incraesed water up take you also need to lower the EC. Just drop the relative humidity a few points (3 or 4) at a time until the plants show signs of inadequate water or until the plants quit taking up increased levels of water. With indica and afghani strains you will be quite surprised at the increased water/nutrient up take under maxed out conditions and lowered relative humidity. They are from a hot dry climate after all. While in their native lands they perform better when the get coastal winds bringing in increased CO2, the researchers found they respond to the increased CO2 brought by the winds not the increased humidity of the coastal winds. Winds in areas further away from the coast also provide the same benefits and thet are dry winds.
Don't do the thing with putting the tall plants around the edges and the shorter under the center of the light that is commonly done by a lot of growers using large wattage bulbs. Instead if your tray watering system will allow just raise the trays up that contain the short plants. It makes no sense to place the best growing plants out to the edges if they are the plants best responding to the conditions supplied. Movu ing them to the edges is pemnalizing them for growing better. Doesn't make sense. I digress.
At least 5 pounds, likely more than less.
These people will take you in the wrong direction with your plants bro ..trust me I grow medically for a dispensary in LA .
!!! looking forward to seeing your results, and I bet you'll get at least 4 lbs