My 8" travelled in the boot, on a blanket. My 12" travels in a trailer, sitting in the original foam semi-circular packing - one each end - all sitting on a thin carpet. It cops some bouncing around.
Never a problem and hardly any effect on collimation - just a tweak needed.
Make sure that the three lock screws are done up snug on the primary before you transport. Also make sure your three collimating screws on the secondary are firmly against the secondary holder. It's the secondary I've worried the most about - I don't want it working loose and spinning around.
Also useful to pull a rubber band, or similar, across the large end cap so it doesn't fall loose. The rubber band can be connected around the spider knurled screws.
Happy travelling to dark skies.