I thought the suspension thing was the issue. If I had the money I would buy the kind of rack where you place the bicycles in like this:
OOOOOOOO, nice. I doubt there is an adapter for snowboards.
My cheap crappy rack did hold up for a 2,000 mile trip and I owned it for 2 years. I remove it most of the time and store it in my closet. Another issue with this type of rack is blind dumbasses backing into them in parking lots. This happened to mine and now it has a sketchy tilt.
A roof rack would be difficult for me.