For those rather unfamiliar with Middle-Earth Lord, Cardolan was one of the Sister Kingdoms created when Arnor split in TA (Third Age) 861, the others were Arthedain and what became known as Rhudaur. It's been postulated that Rhudaur's original name may have been "Rhunedain" ("East-Edain").
I'm wondering if the Lord Saruman might be more interested in expansion into Dunland and Enedwaith to the border of Cardolan, and perhaps seek and alliance with Cardolan.
I'm concerned about taking an unnecessarily aggressive stance toward the Lord Saruman. To quote Queen Amidala from Star Wars EPISODE ONE, "I will not condone an action that will lead my people to war." My people are the Cardolani, and while I am not in any sense a spokesman for all Cardolani, it makes very little sense engaging in a conflict with the Head of the White Council, much less the Head of the Istari.
We all know that Saruman has many titles, many by right. Besides those mentioned in the previous paragraph; Beren, Ruling Steward of Gondor, in TA2759 granted Saruman the Keys to Orthanc, making Saruman Defender of the West (de facto). Saruman claimed Lordship of Isengard in TA2953, effectively becoming Leader of All the Free Peoples and some add to that title "on Both Sides of the Hithaeglir (S. Misty Mountains)". If that be so, the Lord Saruman could be considered Leader of the Free World, which is an unofficial title used for the United States President. (I'm not sure how Queen Elizabeth II would feel about that!)
We all know that the Lord Saruman had his foibles, but perhaps with the right diplomacy, he would be persuaded to consider a more peaceable westward expansionism into Dunland and Enedwaith, and conclude an alliance with a restored Kingdom of Cardolan. The only problem being, of course, would be discovering a proper heir to the throne of Cardolan.
While Calenardhon was ceded to the Eotheod by Cirion, Ruling Steward of Gondor, in c. TA2509, this caused considerable hardship for the Dunlending immigrants that had lived in and developed the area since the Great Plague of TA1636. (In North America, this would be similar to the United States Government forcing the native Amerinidians from their lush, green ancestral homelands into inhospitable areas).
My person opinion is that the Lord Saruman, in seeking to reinforce his position as Defender of the West, was reluctantly led to a decision that "played to" long-standing Dunlending hostilities against the blond Rohirrim (whom theu called "strawheads"). I could go into more detail, but that is for later on.