For some reason, I like the Hammer Truck. Along the same lines, while it's not a recumbent, or even a crank forward, Surly has a model called "The Big Dummy" That is the same idea.
I've thought of having another rear triangle built for my old Cruzbike conversion frame. It's a dual suspension mtb frame and I thought you could take that rear section out, have another made that would extend the wheelbase, add the built in pannier racks, or something along the line of the rack system on the Hammer Truck and make the whole thing bolt up solid; no suspension. The added wheelbase should make the ride smooth and in theory, you could always bolt the suspension triangle back in for a sportier bike.
Mark
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Bicycling is my drug of choice. Followed closely by beer.