I think the geometry of it just works out better for TKP… You need some meat where the kingpin attaches.
Also, I’m really not digging the double kingpin truck term. That’s sooo… non-descriptive and confusing.
There’s loads of designs that have multiple kingpins going on.
I really think series kingpin and parallel kingpin make so much more sense.
Of course Voxter falls in the queenpin category.