At this point, what you have is a tandem tricycle. In order for the cook to access the grill, the rear (stoker's) saddle has to be turned back. Some seat posts, especially the expensive ones, don't have the range of adjustability to do this. The cheapo seat posts of very inexpensive department store bikes work great.
A platform needs to be made from plywood and attached to the basket's frame (with the basket not in place). Attachment is done with a series of holes drilled through the plywood, and secured with zip ties. Note that there must be a gap between the plywood and the rear triangle so that the cook's legs/feet can fit through.
The rider must be strong. Joe is pulling about 400 lbs of metal and flesh. It helps that he's a bicycle racer. We worked out a technique: I'd cook and hand off the sandwich to the rider, who would then get in front and receive condiments from Joe.
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