How about a heavily customizable health patch? Each normal and custom sprite as well as the other sprite types that can interact with the player (extended, cluster, and I think one minor extended?) should be able to take off a specific amount of HP, it should be possible to increase the player's maximum HP by finding collectibles or triggering event flags (and those also save to SRAM), and it should be easy to change how it's displayed if you want to: regular Layer 3 status bar, sprite status bar, numerical, continuous meter, hearts, pause menu, HUD above the player's head, whatever. (Mind you, I know more than enough ASM to modify patches like that, so it would be more a case of flexibility than anything.)
Or if you'd rather do a sprite, how about the Stilt Guys from Yoshi's Island? Daiyousei format would be best for me, but I can convert them from whatever.
I'm working on a hack! Check it out here