Hm! Interesting... I'll give that a go! Thanks for the advice. :)

I can assure you it's not useful at all. You're much better off converting the cost of the PD into more armor.
Another thing, which is a typical mistake, is that you have way too much power generation.
Here's what I think you should do: https://imgur.com/KOFHR4E

I do have some builds like that, but of course that exposes the infrastructure in front to damage from mixed-arms ships with, say, ion cannons. Figured I'd give this a go, haven't extensively tested how useful it is though.

Why not have the PD in front of the armor to start with? That way you'll reduce incoming damage and still have the armor.

Haha. They're a backup measure. If all the armor get stripped, I have a way to intercept the missiles that might bring down the shield generators. It was a hypothetical play.

And your choice of point defense position is... interesting. ;) (they can't shoot)

Using only armor is completely fine, but you'll need MUCH more of it. A good example are those monolith ships that barely use any shields - they have massive armor slabs. Don't shy away from being a slow brick. That's your lore, you say. That also means get rid of all these thrusters (and make the engine rooms you do keep accessable via a corridor - speeds up crew massively) - these open thrusters are a massive weakness you don't need. Just travel accross the sector via a fast hyperjump-beacon-scout that you jump to again and again. Your combat ships don't have to go over 20m/s, if they're not kites. Also, you can replace the majority of your ammo storage with a few factories, since they only need a fraction of the storage space in sulfur which they can turn into much more ammo - saves weight & money.

Your ship will be competitive, if you can go toe to toe with a similar costing ship designed by another player. EuroSpace ships are a good candidate, if I do say so myself. ;)