How to handle stairs by hand

Don't yell about reposting. The other methods discussed won't work for me due to the nature of my project. Trying to allow for bunnyhopping, surfing, etc.

First, I can't use a character controller, I'm actually pretty much writing a new one from scratch as the one given has several unchangeable settings that prevent it from being a viable option, namely the capsule shaped collision box.

second, I can't use an invisible-slope-for-stairs trick, as the slope would behave markedly different when jumping repeatedly on it.

my character object is equipped with a rigidbody and a box collider, though I don't actually know if both of these are necessary.