Make hunting the wumpus into an actual step in the progression of the Ranger quest, rather than just having a level inspired by it. For instance, the wumpus that appears in the quest is much more powerful and can kill the player in one hit, and must be slain in order to progress beyond its level (even if the justification is as flimsy as “It isn’t safe to proceed while the threat of the Wumpus remains”).

Add a bit to the monst struct that tracks whether the monster is hiding on the ceiling or not. (Only valid for things like wumpuses, piercers, and perhaps bats but not actually since bats don’t roost on the ceiling when inactive.)

Then, when polymorphed into a wumpus or piercer, you can use < when not on stairs to climb onto the ceiling and > to climb back onto the floor, but only when adjacent to a wall.

When you ride a clinging monster like a wumpus, you get a message about all the blood going to your head.