Hunter class is fine for fat shafts but as Matt mentions,you may cost yourself when stepping back.
I would highly reccomend when shooting long stakes with fat shafts that you have a higher energy setup that has a little ke and momentum to fight off some of the wind drift and other factors that make fat shafts unstable at distance.Most people have no problem with this,I did.
When I won the ASA ky state shoot I believe I was shooting normal diameter shafts.I had a low energy setup and have never been able to shoot fat shafts at distance that the groups wouldn't open up at distance.I believe ACC's was what I was using.
Besides,you are only talking about .020 to .040 advantagein most cases with a fat shaft over a regular shaft.The diameter must be divided by 2 to get the advantage.

If you drift that much,advantage lost.