Don't top and start to flower at about 8 to 10 inches. 2 1000 hps man are you going to be happy. Try to get hortilux bulbs when you can and see the difference. You will be tieing up stings to hold buds up no big deal.
alwayssleepdeprived, Has got you covered on the areo. I don't have one. Good advice.
Get an RO system off ebay cheap and worth every dime. Sounds like you been doing home work your on the right track for sure. Keep your rez temps 70 or just below that. Man wish I could see them finish.
Check out my grow LOC NAR1958 (papaya) it's back a ways last year but still here. 3 inch netpots, ten gallon drip, 5 gallons water, 6 plants. A little over 3/4 pounds. 1000 watt hortilux.