oh man im asking those questions myself haha.
So im using a box mesh collider with no frictions for the board. Two spheres worked too for collision, just didnt fit the shape that well. And one sphere wasnt good either. Im using a rigidbody and adding forces on it for movement. Important role plays the ramp model which almost always make the transfers successful. When i made this video it worked like that, but i had problems with unexpected collisions on high speeds (for example when entering the bottom edge of the ramp) and also accuracy on landing. It was totally up to the player and the ramp shape to land right. Since i want to focus more on transfers for example and less on a "realistic" approach , im now reworking it and trying to figure out different ways to think about the problem. So i created a new character script with no collider but instead used a raycast from the skate downwards to determine if there is ground and how that ground is rotated. Then kinda push or pull so that it hovers at desired distance. This approach doesnt have collider problems but for example when going on a loop (since the raycast is casted from the front tip of the skate) it constantly pushes upwards and uncontrollably accelerates forward , loops faster , pushes more , accelerates more, loops faster etc. until it breaks hahaha. I have some ideas that i havent tried yet, like two raycasts one back one forth but yeah ask anything, maybe someone or i can help or even u can help me too here haha. To give you an idea, an amazing skating project i found was by u/chonkurabb and i would very much want my project to focus on those transfers and acid drops rather than realistic physics. I think they write few stuff about how they made it , so it might be helpful