i maybe spend too much time on the first outpost..

[Bwixie]

every time i start a campaign i go through the inventory of the sub deconstructing most objects like diving masks and flashlights, unnecessary weapons and tools, and then fabricating supplies out of those.

i personally find diving masks not too useful, if you need a diving mask you either fix the leak fast enough without o2, or you need a diving suit.
sprayers and flashlights too, i've never needed more light than provided by a diving suit or sub's emergency lighting, nor needed to clean or paint anything.
i will probably dismantle some extra plasma cutters too, don't need more than 2 for wrecks or mining.

honestly at this point i should just edit a sub to be already set up, but i like the random generation of some cabinets giving more or less options.

[Buggy Boy]

Nothing wrong with clearing out unnecessary stuff if it's only you going to be using them, but consider that the bots may use masks and welders. Also consider that deconstructing and fabricating uses quite a bit of power so for the sake of gaining some materials you're losing some fuel. I'd hold off deconstructing until it's more necessary, or do it when hooked up to a station if the sub still gets power that way (with the reactor switched off).

[FourGreenFields]

Diving masks are usefull in ballast tanks. Also if you turn off the oxygen generator for a while, or it fails and isn't repaired soon. I just keep one mask in the inventory, not like you need all the inventory space (most of the time, anyway).

[Greb]

If you're not spending 30 minutes at the start of each Campaign sorting the submarine to your liking and deconstructing all the "useless" stuff then you're playing the game wrong

[Buggy Boy]

Oh and for random cabinet contents you can add a few key items to a cabinet in the sub editor and have Auto Fill ticked, it will add other 'random' items based on the cabinet tags added. Of course this may mean torches and other stuff you maybe won't need, but they will supply components and materials once deconstructed.

Even if the contents of the cabinets is the only thing you change, you will need to either start with the sub or buy it during a campaign, though you could set the price really low to reflect how different it is from the vanilla sub.