You're saying you're having issues killing level 68 enemies on a level 70 class? I would recommend using a chocobo as an easy fix or reading up on a guide to help improve your DPS as the only reason low level mobs should be killing you is if you aren't killing them fast enough.

I can and do pull multiple level 60-68 mobs for my weekly centurio hunts on bard, and do fine even with no chocobo. I even do my weekly elite hunt (which is level 70) with minimal issues.