The stock fogs taper up.
If it weren't for that, the 6" would work perfectly.
You could try the next size up, which is an 8".
However, that might be a little too big.
Best bet would be to take your Rig over and just ask if you could try one out in the parking lot.
Most places would probably be okay with that because the packaging goes right back together on those KC Stone Guards.
If you don't have a local shop,
just make sure the online place has a good return policy.