I just did the latest whale stages and I have a full boat of rainbows and it takes a full boat of rainbows or really strong bloomed golds (like peach) to clear it I bet. Its worth it if you can do it as there is 15 half stam potions that are rewarded.

The lack of girls upgrades/buffs, lack of solar buff(which makes a huge difference on whale), and lack of blooms is finally coming home to roost I am afraid.

EDIT
I just did all these and many more above this one in DMM with 70-75% golds without issue as comparison.
and DMM added a per turn damage gauge last week that really helps with team construction.