The VF-1D is far more complex than you guys might think. Even Yamato's attempt to make a great looking and true VF-1D toy has eluded them. It's not a simple change to a longer cockpit and viola you had a VF-1D, it really is much more involved than that.
The VF-0D on the other hand is pretty straight forward. The cockpit is made larger by opening it forward. Then the pilot gets is moved forward and a space is cleared a bit rearward, as well as extending the cockpit rearward. This is sufficient to make allow the both pilots to sit tandem and not look so crammed in the allowable space. The remainder of the changes are mostly add ons to make the VF-0D complete. The heatshield is extended via an additional plate attached to two pivot points on the lower (forward) end of the existing heatshield.
From what I have seen, Yamato misapplied their interpretation of the VF-1D. Everything they did with this V.2 should have been used to make the the VF-0D.