Over the past 3 weeks, I had two long drives (~1300 miles) which spanned 2 days both times. We averaged 600-700 miles daily (~10-12 hours), with brief gas and rest stops and a quick lunch stop. I drove for more than 50% of the time.
I wore the psi-bands Breathe a "Psi" of Relief! | Drug Free Wrist Bands for the Relief of Nausea
that I had purchased for a long ferry ride last year. I also took a Valerian capsule before bed.
And <drum roll> I am pleased to report that after these 4 'driving days' I did not suffer from the entrainment issues that had plagued me on previous long road trips.
(For the record, I opted to try the Valerian before bedtime, as some of the other items might have caused drowsiness while driving.)
Thanks for all the suggestions!