Here's my setup: http://www.edshipyard.com/#/L=60N,4zh4z ... E7dq10i0nE
If you turn the cargo hatch, frameshift drive, fuel scoop and docking computer off you'll end up 0.03 MW below your max power output so everything runs fine. If you upgrade the life support to A and have it turn off when the weapons are out you can get another 1 MW to play with if you want to fly it that way (you'll have 25 minutes of 'guns out' time before you need to dock or suffocate ). In my experience so far this setup is extremely agile, very fast and very powerful. The ship will start to overheat if you're firing the lasers nonstop and boosting but otherwise I don't have issues. I just chucked the hull reinforcement on because I had nothing else I particularly wanted. Also I made the fuel scoop big because class 4 shield cells use too much power and I don't enjoy staring at stars : )
If you wanted to tweak it a bit you could change to burst or pulse lasers to save power and ramp up the defences or something but I find this build works extremely well for me : ) I'm loving it!