Help with proper use of my grow tent

I have a 2'x4'x7' tall tent. Im working with a 400w HPS. Im just looking for some brain storming seeing as everyone has their own ideas, but my goal is to have a perpetual grow. Im using dirt right now but wondering if i should make the big switch to Bubble Buckets. Anyone have any ideas. Open to any and all ideas.

I am personally flowering in a 2X4X6 foot tent with a 400W HID and 320W of CFLs. Bubble buckets are pretty easy and you could probably get about two or three in there if you wanted. I also have a 2X2X5 foot veg tent. I will start veging another plant when I am about halfway done flowering the one that is currently in there. My plan is to use all 720W (will be 812W after Im done adding all my lights) to grow one giant dense plant. My last plant was 77.1g, even with all of the mistakes I made, being my first grow and all. The other thing is to make sure you have good ventilation. Without that you arent going to be able to do much.

Heres what Im working with for flowering.Iif you bush your plant out good enough 6 feet is too much height.