I've been working on the best possible strategy for trying to solo the "Journey down the Anduin" scenario with the best possible score. So far I've had the best success with moderate to high threat heroes, but I'd like to give a low threat group a try. My theory is that with the right draws I can make considerable progress putting out allies and questing before I have to fight the troll and the other high threat baddies.

Can anyone recommend a really good low threat group of heroes and a deck to try to master this scenario?

I beat it with Eowyn, Dúnhere and Bilbo at a score somewhat below zero. I don't have a list of that deck, but it included some healing and card draw from lore and all about gandalf and threat lowering as well as northern tracker from spirit.