In BikeCAD version 18 we can design a bakfiets style cargo bike. You'll find the option for this in the headset dialog box. Maybe not the most intuitive location for this control, but this style of bike does have two headsets so we'll start there. Once the bakfiets option is chosen, we'll find a new section in the tubing dialog box to configure the middle head tube, the length of the front head tube and the distances in X and Y coordinates separating the bases of these two head tubes. Once you've spaced out the head tubes as desired, you'll likely want to connect them and you can do that by adding an extra tube from the middle head tube to the head tube. You can also go to the rack and cargo section and add a bucket. The bucket is located by X and Y coordinates from the base of the middle head tube. For non-bakfiets designs, this bucket option is still available but it will be located with the respect to the base of the regular head tube and you'll likely want to make it a lot smaller.