OK, I’m on a roll, and on another rant. That what insomnia does to me.
If you look at the 1650 northwest in the Gunboat variant, you will see that Cardolan/Arthedain is fairly well-matched against WK/Rhudaur, and if the DS are sly they can even slip past the Free to take key popcenters.
When I play Cardolan I pray to Elbereth (and send a T1 diplo to request) that the Dunlendings send everything they have north. They really have to, in order to cement the FP victory there. They could hold off a turn and see if the Dwarven T1 diplo says he is moving against Rhudaur, in which case this would free him to send cavalry east, if he wants. But apart from that, the FP really need his forces to hit Rhudaur and help protect Cardolan against an early blitz.
This can literally lose the game for the FP, or at least lose the northwest. IMO of course, the Dunlendings MUST use their initial armies against Rhudaur and continue hitting hard until victory is assured, and only then send aid to his North Gondor partner.