The key point I think will cause you to fail is the mindset of thinking you need to beat the next boss to progress.

The way I see it is you beat the boss for the current area when you are already ready to tackle the next area.

Scout for food
Upgrade your gear
Then you should be scouting for a Swamp area <you want to find one with crypts near a black forest copper patch to make life easy>
Scout out Swamp for food items
Set up base by swamp and copper to prep for Iron

THEN you kill the boss of the black forest.
If you are struggling to just make a foothold in the Black Forest you shouldn't be looking to beat the boss. He will not drop anything useful to you if you can't survive the black forest yet.

Avoid rafting in ... scout around on foot and find some copper near the edge of a meadow by some water. That will be an optimum place to start your black forest incursion.