Unfortunately,
I’ve hadn’t thought of taking out the RTC battery completely … that could work, but if you don’t constantly have an internet connection, you’ll be resetting the system time yourself.
You can also leave a power bank plugged into the laptop. That way, you can keep both of the laptop’s batteries fully charged while traveling. Could solve the issue depending on how often you can plug in. Having a power bank tends to be a good idea anyway given the poor battery life of the Framework.
Edit:
I use this power bank, but there might be better ones now. Haven’t shopped for them in a while.