Power bank for iPad 8th generation

Something like the Mophie USB-C 3XL?

https://www.zagg.com/en_uk/powerstation-usbc-3xl

This one weighs-in at just over 1lb and has 26000mAh capacity (almost the highest capacity rechargeable battery that you can legally carry on an Airline)

Look for the largest wattage/volts you can afford.

One that has a solar power option maybe a plus also.

The higher the internal battery wattage/volts, the more expensive it will be.

Purchase one that states that it can fully charge a tablet, not just a phone.

Best of Luck to You!

Note as your shopping that large batteries that can charge an iPad fully 2 or more times start to get heavy. In my car I have a NOCO Boost jump starter batter kit that can also charge my iPhone XS fully about 6-8 times, or my 10.5” iPad Pro at least 2-3 times. But it also weighs about 6lbs. Admittedly it can also jump start a v-6 or v-8 car or pickup multiple times on a single charge, so over kill if not needed for that specific role.

But the larger the power bank, the heavier it will be, and the longer it will take to itself charge up each time. Since it’s a road trip, maybe the size and weight is not really an issue though?

Plenty of power banks on Amazon.

Find one that is affordable to you and purchase one.

Best of Luck to You!