Hmmm - Not sure, since you don't have stock hard tanks, kinda throughs me off a bit. I can tell you the X2 does like a 60/40 relationship, rear/front. What are you doing for KGB/forward ballast?
My set up was this:
rears - Stock 150 + 450 bag - 600lbs each side - 1200 total
KGB - 250 stock + 350 in walkway - plus a body in the bow @175 - 775 total
approx 65-35 weight differential
All full the WB wake was about as good as you could get for an X2 - 70' line length max and about 21-22 mph
For surf, only dif was one rear side empty and bodies on the surf side. If we only had 3 people, the 350 would be moved on top of the surf side seat and keeping the KGB full.