u can try using lorna attuner art too, she heal quite alot of hp and invulnerable while using it, if combine it with your trick u already got 2 free use of lorna heal and 4 healing ward

I believe I used:
Equipment:
Abelia's Bracelet (50 heal potency)
Aster Bangle (80 healing potency)
Cetus totem (+1 heal, full heal when below 15% hp once)
Primordial Heirloom carapace (5 healing potency, likely not needed at all)

Relics:
Leg Enhancement Gear (Slightly increased movement speed)
Ward Propagator (Faster healing animation)

I don't think any other relic helps since the damage mitigation ones don't work on the environment.

You kinda want to water sprint -> burn the autoheal and keep sprinting -> Heal when needed, dash, heal again -> start another sprint until you have to heal again -> Heal, dash, heal -> sprint to the end. Should be totally doable, good luck!

What equipment and relics did you use? I've tried equipping everything that raises your healing but I can't make it past the 3/4 way point.