When you consider the scale the maps will have in ETW (I believe they'll be much larger than those in M2TW, as a lot of artillery will be used, which will have greater range than M2TW units) then having artillery bombardment from outside the map seems unlikely....after all, the gunners in that era could only bombard a visible targets right?
Anyway, like it has been suggested before, with no response from CA, ships could be made like stationary batteries of guns, with limited controllability.