Good work, Skyder! (Actually,I think, you could place a fire extinguisher where you wanted; you can always encase those pipes...of course depends what is flow and capasity
But do you have enough room for mine laying? I mean you'll need at least 2,2-2,5 meters "free"(+HVAC installations) to be able to lay mines and above you'd need free space to clearing equipment; not helodeck.
But again, this is interesting concept and very well drawn!
I'am from a country, where mine laying and clearing are top priorities for Navy; so, carry on!