I would do as blackelk said. Tag the quarter with evidence of sex, then keep the other portion in your pocket. That way carcass tag is on the "carcass" and the other portion is on your person.

Now to get tricky, what if you decide to bone out the meat to pack it back. What do you do about evidence of sex and tagging? I am asking your thoughts as I do not know.

I would leave testicles attached to a big chunk and tag that game bag at the truck with the carcass tag and then go back in to finish up the packing process.