How to edit player collision? Is it possible?

[Blezmo]

So far, I've been editing the nodes on skeleton.nif file for Skyrim. Niether increasing or decreasing the bump node seems to affect collision in any noticeable way. I used NIFSkope to edit it.

 

For example, I tried to see what would happen if I doubled the size of the bump node to make the collision box bigger for bigger characters, but it didn't work and the character still clips through objects.

I've also tried doing the reverse for small characters and there's no effect for them either.