Holla!
This question and your comments leads me to ask myself if it may exist an alternate solution for this problem. What if:
We connect an external batt while starting, that will reduce the current drain from the inboard batt, allowing us to have a smaller onboard pack? (like we do with the fuel and the taxi tank).
Or, having just having a really big capacitor on the ecu line ? Ok, this one is wrong…
But, you get the idea, address the problem from a other angle, what’s your thought ?