There are at least 3 tricycle cubs posted on this board and likely others out there. George Willer and I both made the front spindle although differently. If I was going to do it again, and I may make another in the fall, I would make the front spindle completely different than what I did before. I thought of another way, easier, faster, cheaper, looks better.
The front spindle is not the labor intensive part, if you want to narrow the back, that is the part that sall the time. If you leave the back as is or wider, then not really much to making a tricycle cub.