This is the hunting setup I used at this level. You are welcome to try it for yourself but this setup may not work for everyone. Stats shown are without buffs.
This is the armor based setup I initially tried since I could get more damage, but it left me losing too many battles to be effective and the damage still wasn't enough to constantly two-hit.
This is a defense based setup designed to keep the creature from hitting me while maximizing my own hits. Unfortunately, I was still unable to obtain a high enough damage.
Results
Defensive Setup: ~1,800 Stamina = ~35% XP + ~170,000
The defensive setup seemed better overall but part of the discrepancy was caused by using more stamina (100-200 more) with the defensive setup than the armor setup.
The armor on the Centurion Beetle Larva demands that setups have as much damage as possible. Unfortunately, neither the armor setup or defensive setup were adequate. To level up more efficiently, go back to Ofron Islands (West) and continue to kill the Benthius.