If traveling by a vehicle and you would be inclined to use it along the way ( and who wouldn't be
), just charge before actually leaving so it will be ready to fly if you need to.
You would normally have it in the front, not the trunk, to get at it if you see something cool so you can get at it asap... just like any "normal" camera on a road trip.
The batteries will automatically go into discharge to a storage level after 9 days, a recent change to the
Air2S (I think it used to be 4 days), so if going by plane, etc maybe take/pack them after they reach that point so they are already in that storage state?
Although the info you posted regarding 50% for transit is a good idea it is outdated now with the Smart Batteries.
I have taken many airplane flights with drones/batteries in the carry-on and have had up to 3 completely charged batteries and have had zero issues.
I have taken multi-day "land" trips by car and motorcycle, also with fully charged batteries, with zero issues. I have even charged them after a roadside use (after they cool-off, of course) using a car charger... in the tank bag on the bike or in the car as I continued the trip.
In other words, don't stress it!!