Then fucking hell, deploy the 12 pops and 2 hunters by Greenvalley and the White Halls. I'm not saying no. Do whatever we gotta do to procc the Mobs into Fanaticism. It's our only realistic hope.
We don't have specialized scouts because they're off with Deer. We don't have better communication tech than the lowlanders do. We don't have better river-navigation techs. Realistically the lowlanders will detach a segment of their armies that will paddle upriver, thus flanking our harassment force by river. We know that because it's part of the A, B, Cs of lowlander warfare.
I'll tell you what'll happen. The hunters will go off and we'll never hear of them again. One and done. Now we'll be down two critical food producing pops. The last thing we need is to be defeated in detail by their superior mobility.
My dude, have you ever heard of the home field advantage? Where the people who live on the land actually know more about it than invading troops, their communications I don't know much about, their mobility.... they're horses in mountains, worse, mountain forests, they're great on plains, not as good on rough terrain
If they did send part of their army ahead and such, um, they'd already be doing it at the river (would actually be the best terrain of the area for their horses, if they detach a segment of their forces then we're also dead on the river.
The reason why I believe that we could get away is because, at least from what I know, our land ain't clear, we can melt back into the forest after attacks, and after a few times if being led into traps they won't pursue very far. And really dude, even if what you aid were true but they wouldn't do exactly as you said for the river crossing battle for some reason, we are still screwed attempting to stop them at the river without some ridiculous rolls
Basically, it's doubtful we will be defeated in detail, I believe, because most of their army shouldn't be used to the terrain while we are. Guerrilla warfare has been used since time immemorial by smaller forces to delay and defeat larger ones for and reason, it's effective, and I don't see much reason why it'd stop being so here, your arguments both don't make sense to me and don't make your plan any more attractive
Edit:this came off as more rude than intended, sorry about that