Rotation offset when stabilizing

I'm using a 2-point tracking setup to stabilize some video because I'd also like to stabilize it's rotation.  The big problem is that HitFilm assumes that 0 degrees of rotation of the first frame is the desired resulting rotation.   So, all rotation stabilization is based off of that (incorrect) rotation.   I can't find any easy way to add a rotation offset to all of the rotation transformations that the stabilization algorithm produced.

With standard X/Y stabilization, HitFilm solves this same problem by using the "Anchor point" as the stabilization output, and then I can offset this with the "position" transformation.  

Anyone know how to do this with rotation?