Sorry to say, but I fully agree with Jorgen.
It is a single player game, so you can do whatever you want. You can also use it in a multi start campaign, or perhaps in a pvp tournament in discord if the rules allow it.
But it is not a "roleplay" or a "balanced" thing.
Using the designs above is not something that is WAI. You are purposefully using a quirk of the mechanics (the volley mechanics and the fact that larger volleys are targeted first) to create an attack that simply cannot be stopped AND is still very cost effective.
The game is simply not balanced for it at all. As such, no NPR or spoiler can deal with it, because in the end, it's impossible to stop unless you build a fleet specifically to counter it.
Once again, it's not the tactics that I'm against. You are of course free to use anything you want in your games, who am I to judge that. There's far worse ways to break the game, like using SM and add stuff.
Just please don't tell me it's a "roleplay thing" or a "WAI tactic". We all know it is not.