Always make new content for V4/M4 first, even if you don't plan to release a V4/M4 version. V4 is the lowest common denominator and all conversion utilities works with it.

To rig in Daz Studio

In Daz do not use auto-fit and do not make a version for Genesis-Base made to stretch to fit other figures.(The recommended procedure from Daz). It will look like plastic. Instead, resize your V4 model in a modeling program to fit your target figure.

Then to rig this new obj, use the Transfer Utility with two special settings,

Item Shape: Current

Reverse Source Shape From Target: Check

That is all there is to it. I promise you that you can hunt for months without finding this information. And, this will work for Dawn from day one you can be sure of it.