Off-topic:
Speaking of the Xtracycle, I borrowed a friend's Surly Big Dummy to make a beer run. I put a 12-pack, four six packs, and two bags of ice in the saddle bags. Had I put the cooler on top, I could've easily doubled the load. Carried the beer rather well, the weight being low and on the back wheel. I had a crowd of people watching me load the bike at the gas station.
For the OP's bike, I also vote for Xtracycle conversion.