RF focused build would do most of its damage from standing still and attacking(and would also have more hit dmg than DoT). I feel like in current GD that is a bit worse off (in high SR/superbosses context) but that is just from my experience and without testing.
Edit: nvm it already exists by Crabturtle [1.1.9.7] The Revenant King - 2H Ranged Vitality Oppressor - All Celestials, SR90, Cr 6:13
Also one of the top20 builds has a very similar concept to that with dual Gargabol pistols.