I think last year it was decided that realistic versions of the animated clones are acceptable.
I don't know that for sure,I sent a pm to the DCO to find out.
If you haven't done so already, go to the Clone Trooper Detachment (
http://www.clonetroopers.net/) and post the question there with your WIP pictures they would be able to tell you for sure.
It looks like your belt is an animated belt and not a movie version, I think if your doing a realistic version of Rex it has to have the whole movie version and not mixed animated and realistic.
Looking good so far