The first and foremost step should be to ramp up damage on the tanks whilst also tuning their self healing downwards somewhat.
Go right the way back to Coil Turn 1, the earliest example of a no healers run I can find referenced was in April 2015, not far off a full 2 years after BCoB's release and after FCoB.
https://www.youtube.com/watch?v=f1ztYeiDr3A
Even with the gear disparity, Caduceus still packed a fair punch towards the end of the fight. With that sort of damage coming in throughout a modern fight you're not going to be able to reliably survive it without unrestricted healing as it's just too spiky to deal with consistently.
IMHO course correcting tank damage should even take priority over any adjustments to raid wides. Remember when Regen used to be worth maintaining on tanks in Savage/Coil? Now it's barely worth the GCD outside of specific windows like P4S Pinax.