I would be careful if you have any PCI cards or even risers, they can vibrate loose so using some non-conducting epoxy or even a hot glue gun can help to prevent that. same with SATA connectors and some power cables. To be honest, if you get a shock resistant 2.5" drive, you probably won't have any issues. At my work we have some off-road vehicles which withstand severe hits, harder than any on-road vehicle could and we run 2.5" drives in them without issue. That being said, a SSD is never a bad idea for a situation like that, but you may be fine using a 2.5 hdd if money is an issue.