I aimed a little lower when I was working on that trial - I went with my wife's level 12 BLU to Zegham Hill in North Gustaberg and killed sheep there. At level 12-14, the sheep on the lowest tier check easy prey and have extremely low HP. By level 15 though, all of the sheep on that tier check too weak, but that is easily remedied by moving up to the 2nd tier of the hill.
Just wanted to give you a shout out and say thank you for the tip. I just finished my Varuna's staff for Shiva and Vayu's staff for Garuda. Both required killing sheep and I was able to make the experience a lot less painful by going to this camp. I tried West Ron once and the sheep were just too spread out.
I do recommend bringing some kind of juice with you for this trial. The avatars cost 4mp/tick at that level and your MP will drain away very quickly. I made melon juice because I had limited space and could store more ingredients than if I went with Yagudo. In retrospect, I should have muled away some gear and just stocked up on cherries and berries. The melon juices did help a lot but yag drinks would have sped things up quite a bit.
All in all, I am very happy to get these two staffs finished. The only one I have left for SMN is Yama's staff. I'm stuck on slimes and not at all looking forward to doing it. I finished my Shareeravadi (MAB) and Surya's (cure potency). I think at some point I might make a staff for Levi and Ramuh but definitely not any time soon.
BLM 99/SMN 99/RDM 99/SCH 99/WHM 99/BLU 99/DNC 99/NIN 49/WAR 49/THF 46/BRD 41/COR 40/RNG 38/DRK 37/