Give HiPS at the 17th level of Ranger...., that only turns on when they qualify for their +4 bonus to stealth in natural terrain. This is one of the big PnP perks that could be added to offset the fact that companions are looking at being nerfed, and would be super thematically appropriate if it could be tied into the natural terrain benefits.
Edit: Fixed typo. Repeated assassin instead of ranger. Hopefully the context got through. Sorry about that!
