You really don't need that much duration. Even at 70 duration you get Toxic Lash for 20ish seconds which is good enough.
Use overextended. Then use Transient Fortitude, Intensify and maybe augur secrets and/or power drift in exilus slot depending on enemy levels. Top off with streamline, stretch, augur reach maybe. Lv 1-30 you don't really need vitality and Regen Molt so you can just pack everything into range and power strength.
Ok I'll give that a try. I just picked up Transient Fortitude so I'll throw it in there. ---