@Always Late eh, it's better than nothing. In the sense that we have
some arty which we can use for
some missions other than naval base defense.
Basically if we deploy our artillery it's going to be for very specific tasks and specific missions; we don't have the logistics and supply train to do artillery like the US (King of Battle) or the Soviets (God of War). I know we've got 3 MRLS, what other arty pieces do we have? Because if it's the 105mm towed guns, we can do airmobile artillery shenanegans with our Chinooks sling lifting said arty. (I honestly cannot remember now. Need more Pepsi.)
....and now i have a mental image of a Blackhawk towing an MRLS floating in the air with multiple Fulton balloons.
(tbh if we need indirect fire shens it's a lot easier to have one of 3rd Co's platoons load up with mortars and stuff themselves into a Chinook, with the Chinook dropping them and the ammo off and then they go to town. Otoh mortars don't have the range and lethality of 105mm or 155mm arty rounds, but if they're smart about how they site themselves they won't be too obvious about where they're firing from. At least this is the era where counterbattery radar doesn't exist yet.
Also regards MONARC, there's also the issue that the PzH 2000 turret lacks the stabilisation needed for a naval gun (since dry land doesn't move the way the sea does

), as well as how the 155mm round is optimised for land attack (duh, land attack artillery round) and less capable than 127mm or 76mm in the AAW and ASuW roles (what with the lower rate of fire and lack of AA proximity fuse).
Also I feel I should point out that shoulder-fired ATGM means Dragon, which has an effective range of 1000 meters. So uh... not very useful. -_-;
Well, due to handwavery I think we can assume 'maintenance' isn't an issue.
ROF vs fast targets though is a thing, but I'd assume we'd use it to help against bigger boats until we upgraded our defenses again. Then again we might be stuck on land, in which case it'll be helpful. Basically I think it's a 'T1 defense, better than having nothing' thing.
I don't think latching them to our next combat unit makes sense (b/c a lot of them probably wouldn't do well lugging them along with them). Maybe we can hitch em with one of our armor squads? The MBT's could maybe use them as support. (Of course that's uh turn 7)
The problem with using our piddling few arty guns and MRLS against warships is something I mentioned before in Kancolle fic ideas writing: ship has more guns than land and is always in motion. We've got maybe 3-4 105mm guns and 3 MRLS, the former shoots HE and the latter uses DPICM. That's stuff that'll be less effective on anyting destroyer sized and higher. We have no AP rounds to punch into anything more armored than a destroyer.