So I used Google maps. I just put in Grand Teton as the starting place, put a stop at Benton, and destination at North Port.
It says the trip from GT to Benton is 1,408 miles, which would take 21 hours and 18 minutes under, I'm assuming, regular traffic conditions.
From Benton to North Port, it is 987 miles to North Port, which is 14 hours and 41 minutes.
I don't know that they shared a bank account, so if Benton was the first and only time he used the card (it's the only mention that I've been able to dig up but I understand that doesn't mean it is), perhaps he had money before, whether it was cash or in his own account, and it was basically gone and decided to use her card.
I also don't know if how he used the card has ever been confirmed, whether it was one big withdrawal or several smaller withdrawals. If anyone else has seen this, let me know, but my gut says it was one big withdrawal so he'd have cash to use the rest of the way.