i dont have any experience with flowering with light rails, i have 1 light mover that i use for veg but in flower you need more lumens to gain more weight. so i think you should be fine with 2 lights, i would only do 4 plants per light if you want big plants like mine, keep in mind 1 of my plants will yield 5-7oz per plant, if so your roots need alot of grow space so you want at least 5 gallons of soil, i start to feed my plants hydro nuits after 50 days of growth.... are you using nuits? i use foxfarm ocean forest mixed with happy frog soil conditioner, and for nuits i use sensi bloom part a and part b, super thrive for veg, big bud , for begging of bloom, and overdrive for last critical weeks, then 1 week of flush..