The Better Nether mod has a slime cube that has a prominent flower on top of its head. It completely hides the overhead health. I see the global offset but it feels excessive to me to have the offset be universal for a single entity. My suggestion is definable offsets on a per-entity basis as an option.

betterend:end_slime and then setting an offset as you normally would, 1.401298464324817E-45 ~ 3.4028234663852886E38.