AAL's are the best solution for carrying extra weight, but if I were you I'd try and rearrange things so not all the heavy stuff is out back...not just because of the springs but because of the effect on handling from having all that weight so far behind the rear axle. As already stated, the AAL's will give lift in the back though.
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ChuckH
"Every morning when I wake up I know it's not going to get any better 'til I go back to sleep again!" Al Bundy