Well, the Babel One trilogy may have been intended as a harbinger of the types of ships the Romulans employed during the war. It wouldn't be unreasonable for a single command ship (a couple LY's from the fighting, far enough to avoid unwanted trouble from reaching them quickly enough) to have a remote command section within, where a dozen chambers control drone ships that actually see combat.
That way, the "never saw them" theme is preserved while allowing Earth and Romulus to prosecute a proper space war.
Of course, "never saw them" also likely means the war was fought entirely in space, with no strategic populated worlds changing hands (or, at least, being occupied by the Romulans).
If the Romulans just wanted breathing room for their internal interests, then they may not have had a need to occupy territory, and just cripple the Earth fleet enough to make them stay "closer to home."
Davy Jones
"Frightened? My dear, you are looking at a man who has laughed in the face of death, sneered at doom, and chuckled at catastrophe! I was petrified."
-- The Wizard of Oz