Sorry but you can outcreep him, it's easy.

You just have to move outside your base and he won't fallow you, because if he does so it would be a waste of time.
Hunts and DH without bott of speed can't kill grunts if you have a decent micro, and if he tries to focus one of your grunt with an hunt's slalom or i don't know what, just split your armie...

But the best thing to do (so what i do and other pro Orcs do) is never let him see your grunts, unless he creepjacks you ofc.

You don't really need grunts to buy some rejuv pots do you ??

!!Don't forget this important thing : the time you will have a raider with ensnare + a SH, his whole hunt's armie will be totally useless.

In the case you are an hunt's paranoiac, you can even creep with your BM alone the green camp on the south side (to lvl 2).
(just use windwalk to move outside and he won't see you).