I suspect the logistics of having such a ship close enough to the conflict at the right time would be the biggest challenge. You wouldn't want to drag them around with you on larger ships. I think you're right though, there's probably an appropriate balance of range, size and location where it makes a lot of sense, especially during wartime where it's harder to spin up complex weapon pipelines and simple stuff can be churned out faster.

I think it might work in coastal areas. You could transport them to suitable locations on very basic trailer. Or just on board of a truck with simple crane lift.

In general such things would only travel relatively short distances, be relatively simple to conceal and probably relatively easy to have not too big radar cross section.