If you want the real nightmare difficulty be sure even ground, rest easy and travel light are turned on,
Is there a tactical difference between Travel Light and Rub Dirt On It? You can mitigate both with Regen potion -- unless Rub Dirt On It also impacts Regen? I dunno, never tried either one.
Regardless, Travel Light is mostly about resource management, while Rub Dirt is mostly about don't take damage, but the best way to do health potion resource management is to not take damage, so no tactical difference.
I would have preferred that Rub Dirt On It was based on the size of the party, like, your max health potions are divided by the size of your party, instead of just healing 1. That would incentivize running quests solo. It would also dovetail with Travel Light better.