Yeah, there are a lot of ways to trivialize this fight. My favorite two are on my friends list. One is a level 80 Lancelot with a level 5 NP and a max Kaleidoscope - so he starts combat with 100% NP gauge, and only goes up from there, and once triggered turns everything into chunky salsa. The other is a level 80 Arturia, and basically everything thereafter is irrelevant - activate all of her skills (or at least the first two), put her NP at the end of a chain, and she one-shots all three bosses simultaneously. (You say 70K total, I've seen her do over 150K. Find a level 80. You'll be glad you did.)
This fight is deliciously easy. Moreover, it's actually dropping some useful Berserker skill tokens, which is a huge plus.
Also, yeah, just learned this bit - apparently once a Craft has had its limit broken the max number of times, it gets a performance upgrade. Not always a massive one (for example, the Guts effect on Nightless Rose goes from 500 to 1000), but still... Kaleidoscope. Am I right?