I'm going to try to not overthink this. I'll first see whether I can balance dungeon 7 just by making the enemies harder. There are already some shortcuts that only open when you are wearing enough horse equipment. So the dungeon gets easier as you get more equipped already. The main issue is that you can just run to the boss and beat her, making the enemies harder should remedy this.
Only if that doesn't work will I go for drastic measures.
One other point: Is there a possibility to add more save slots? I used to keep a save game at the state before entering a new dungeon. And use 2-3 slots within the dungeon.
Sure, I'll increase the amount of save slots to 20 in the next update.