Suggestions for traveling roosters.

Hi, I would like to hear how you travel your roosters, I have the problem that when I travel +2 hours some of my roosters get stiff from their legs, some bend their legs like they cant stand with their legs fully extended, others sometimes look dizzy, like they have headache. I travel them crop empty, have used mexican huilila and cardboard boxes, aligned lenghtwise because there are a lot of curves.
Any suggestions?
Thanks in advance guys.