This is my attempt to build Fords of Isen using a thematic deck build around the actual battles at the Fords of Isen. This is a challenge that is not that simple. Your hero line-up is restrictred to Théodred, Elfhelm and Erkenbrand, so Mono-Leadership is the way to go.
Card Selection:
Because the leadership sphere doesn't have enough Rohan allies we include some tricks to get out of sphere (mainly spirit, Grimbold is here for thematic reasons) allies into play: Song of Travel which goes on Theodred, Reinforcements + A Very Good Tale, Herald of Anórien and the sidequests The Storm Comes and Send for Aid. Sidequests turned out to be very good for this quest even with the time mechanics. Every quest stage puts out new enemies so you probably want to stall a bit on an earlier stage and clear the board. Also they are free or cheap so you can play them to lower your hand size, notice that you can have multiple copies of The Storm Comes in play.
Thematic Issues:
Herald of Anórien are the only non-Rohan allies in this deck. Even if Denethor denied help to Rohan, I could imagine that some smaller houses of Gondor would send troops into Rohan.
Heir of Mardil also makes no sense on Théodred, but I use it in almost every deck with him and I needed the readying. For me it's just refers to his noble origins. Dúnedain Remedy is the only in sphere option and there is no Rohan healing ally, so I have to use it too use Erkenbrand effectively.
How it plays:
I found it quite important to kill enemies as fast as possible. I always picked the Dunland Prowler at the beginning and ensured I had 6 attack available. This often meant I could quest with just some allies and had to take an undefended attack if i didn't draw an [Armored Destrier](/card/12059, so I could swing back with all my heroes. On round two I was then ready to go, questing hard and clearing the Islet. Grima helps a lot in a deck with not a lot of early quest power.
Allies that could be used for both questing and attacking like Ceorl, Éothain and Riders of Rohan were quite helpful against this quest that forces you to make progress and kill enemies quickly. The ressource generation of Theodred and The Day's Rising helped to keep my hand size low. Reinforcements is also great in this quest, to play three cards from your hand.
Statistics:
I was able to win five out of ten attempts and I'm very happy with this result. In all my wins I managed to get quickly some of sphere allies into play, twice with Reinforcements + A Very Good Tale, twice with an early Song of Travel and once with two Herald of Anóriens. My loses were most times because I was swarmed by enemies and once because I couldn't get cards out of my hand and threated out after two copies of Pillaging and Burning.