To make a stair that would splash properly all you need to do is combine two objects(?) that are very common in jump - phase and playerclip.
For those who don't play jump often, phase is a type of wall that players can move through unhindered but rockets splash them and can also splash through them. Playerclip basically the opposite - and are used in competitive maps equally to jump maps - to prevent players from going out of bounds.
If you were to create a ramp out of playerclip, and then another ramp in the exact same place out of phase, you could effectively make ramps and stairs that splash sensibly.
Discuss my idea pls