I did most of my suspension stuff in CATIA, SolidWorks' big cousin, but it's pretty similar for stuff like this.
For my 2D sketches, I had the midpoint of the bottom line of the chassis constrained at whatever ride height I demanded (127mm for design, 75mm for ~2" bump, etc), and then I had that bottom line constrained at an angle to the fixed ground line. That gave me control over the roll and bump of the chassis. I then constrained the centerpoint of the tire contact patch to the ground line to provide all the changes in geometry, etc.
From page 6 of my build log. This is my static setup, where I input track width, static camber, etc to get control arm numbers; there's a "disturbed" sketch below it that takes those control arm numbers and locations, and then shows how camber, roll center, track width and stuff changes with roll and bump: