But honestly... I've tried the whole scent thing with my bun and it backfired. He just got more worked up, maybe because his own smell in a small space stressed him out more? Sometimes a clean, neutral carrier with a new blanket is better... my guy would just chew and destroy any familiar bedding I put in there.
Grab some of his used bedding and put it in the carrier now, it makes a huge difference. My bun used to hate trips until I started lining the carrier with his own scent, it just chills them out. Also, keep a small bag of his favorite greens and a water bottle ready for when you stop. Setting up the carrier in his space a few days before a trip can help too, so it's not some scary box. Honestly, a calm rabbit on a long haul is a total win, you must be doing something right.