I updated my flickr page with the 2 main designs I'm considering right now. Nš 1 is straight forward, simpler to build (less weld points), a lot like Tom's Cargo Bikes. But it is longer than a bakfiets "needs to be".
Nš 2 is more efficient lenghtwise, it has a slightly longer bay area for a shorter overall length.
One more thing. I've done something stupid and bought some stainless steel tubing I figured would be a great material. Than I got to know it's not safe to bond that to mild steel (wich the donnor frame is probably made of). So design 2 is an attempt to accomodate both materials; black being mild steel and the rest stainless steel. The two frame sections would be bolted instead of welded together. The idea was given to me by the welder. I'm open to critique and suggestions folks!