I have an 04 Lightning and here is my set up. Center tank, 550 sacs in the rear locker, and 2 550s under the front bow seats. I fill the bow sacs up to the point where you fill the under seat compartments with water which is probably about 1/4 to 1/3 full. I fill the center tank, and depending on human balast, will fill rear sacs 1/4 to 3/4 full. I used to slam the rear sacs full almost all the time, but with gas prices, I am finding the wake with a little less balast to be sufficient. The center balast alone does not put out enough wake for people wanting to go faster than 20 or 21 MPH IMO, but it is pretty decent sized at 20MPH and below but not quite as hard as faster speeds.
I pull people on 60' up to 80' lines and with speeds between 18 and 23 MPH depending on skills and preferences. Faster speeds will require more weight and vice versa.
I also put the wake plate down a little more on the drivers side to keep it cleaner.