two mars 1200 will not cover 4x8 area. you will need to add a mar 700 in between the mars 1200. Mars 1200 is good for 3.5x3.5ft area and the 4ft area slow growth. Maybe the mars 1600 will be good for 4x4 area.
I notice that for led I will need to feed lesser in the beginning until the roots built up then feed more. I use rock wool. I feed about 1x 2-3 day until more root and slowly move up to 3x per day. more root will help faster growth. I use mar 1200 veg spectrum.
The power core plug to the led unit don't hold that well. Top led should add a clip to support the plug to the unit (some of the digital ballast have that support).
The room them is 77f. room humility is little high 55F. The mar 1200 flower spectrum is flowering little better then the full spectrum. all three light is on a 4x8 flood tray.