Saturn 1 and Defender Comparison

It looks like the Defender took it's design profile from the Saturn 1 series from the early 1960s.

The white fin strips running between the black engine tubes give the illusion of the alternating black and white Redstone engines.
The lower checkerboard roll pattern is in the same location as the SA-1 through SA-4.
The black paint from the midpoint of the upper tube to the tip of the nose cone is consistent with the Saturn SA-5.
The fins are the same basic shape of the Saturn 1 series but larger. The extended leading edge fin tip does go into and between the engine tubes.
You might call the Defender a "stretch" version of the Saturn 1 series, most likely made longer for better stability.

Knowing it was based on the Saturn 1 family makes it an even better repro design.