The 100 series range is pitiful, agreed there. My Tesla in the winter has more range than the 100 on a good day, lol.
That said, are you often ready to go longer than a full tank without having to stop to pee or at least stretch out your legs? I'd rejoice if my family made it more than 90 minutes without having to stop for somebody to eat/drink/pee.
I wouldn't sell the car over it. Configuring a custom tank or overcoming the jerry can/rotopax placement challenge seem like a lot less work than changing platforms.
I think the only way a vehicle swap makes sense is if you can swing $50k+ on something much newer and objectively better.
I agree with the comment to spend the saved $$ on coffee. If you double the tank size, best case, you save yourself 15 minutes every 4-6 hours. Seems like a relatively minor thing. If your overland adventure travel is that tight on time that it's a major detractor from the experience, I'm not sure you're doing it right, haha.