Pulled it off after upping assault to 70% and moving Kushinada up to 5th slot.
Strategy was essentially 'avoid normal overdrive'. Spent a long time in raging mode, but that's a simple war of attrition. Cassio/Nike/Kushinada's heals combined still meant that I was losing in the longterm though, as I did lose a couple of members towards the end. Triton's self-heal was pretty handy in this slugfest though.
Thinking about the relative impact of various kamihime here, I'm fairly sure that if Aphrodite was there in place of Kushinada, this fight would've been a pushover instead of close from having enough healing to make rage mode trivial. Belphegor should be able to push the fight into comfortable range due to shortening raging mode + freeing up the ex slot for Black Propaganda.
As for by the time of the first reprint...
Nodens offering a 2500 drown plus a 600 hp per 7 turns regen should help. Apsu having a 750 hp per 6 turns regen (at R!) should also be enough of an upgrade over Kushinada's healing to upgrade the fight to comfortable*. Cupid probably wouldn't have improved my chances over Kushinada though.
*close is when I feel that my win probability is in the ~40-70% range, so varying from slight edge in one direction to moderate edge in the other direction, with a dose of pessimism
comfortable is when I feel win probability is at ~70-90%
And a fight's a pushover when it's at 90%+ as it'd take a damned fluke for me to lose