|Most US ships are designed for one reason Allan to indirectly/directly defend the carriers. If you engage in fire support you either a) drag the battlegroup closer to shore so that both the carriers and the 'monitors' can be defended or b) you attach assets for local air/surface defence. The navy would hate a) mines,missile boats, diesel subs, SSM's etc and a much reduced response time to any threat and a far greater chance of detection of the carriers. b) Is ok if you're a WWII vintage battlewagon with 2ft thick armour and 16 inch guns then all you need is a Type 42 for air defence and the expert European mine detectors. If youre a hybrid ship then you have to have Aegis attached and then the navy whine because their carriers have reduced protection. 127mm guns for fire support are mainly used if the threat has non-existent anti-ship capability or are used at night to support raids. Finally even with these points overcome the killer is weather, what happens to your fire calculations when the ship is in a force 8 gale. ...............................Swede
p.s. If your opponent has decent counter battery radar then expect a salvo of MRLS ICM munitions, hence the Aegis requirement.
p.p.s Hope you're heavily armoured monitor can move quickly and still have a low sound signature at low revs otherwise hello Mr acoustic torpedo
p.p.p.s Big square flat facetted gun turrets act as wonderful radar reflectors.