What is your suggestion?

I request that the mounting position attributed to resized entities you mount be separate from the height of the hitbox as a new scale type. For instance, it could be called pehkui:mounting_height, and setting it to 2 would double the height of the point riders of the entity visually will be at without doubling the hitbox height. Currently, the actual height of the hitbox is what determines the height that any rider is positioned on.

I second this suggestion, I'm having a lot of trouble with players floating above and inside both modded and vanilla mounts and this would easily fix it.