You should be able to find the suggested footprint from the manufacturer. I am not familiar with those lights.
I do use 7 gallon containers and run 1000w de’s, the footprint for each light is 5 ft or so but I set them up at 4 feet. In that 4 ft space I do 4 plants and veg for 4 weeks or so. I aim for 1.5-2 lbs per light.
figure out your footprint and then you should be able to plan it out. If you are going to do 7 plants, I’d veg for two or three weeks max and use 5 gals.