You may have problems with your credit cards. Most NA credit card networks will classify small fill ups with gas every two - three hours as likely to belong to a stolen card and shut off it's access until the owner can be contacted, which could be hard if you're on the road. The same can occur with regular cash withdrawals every day or two.
I've tried contacting the card issuers in advance to warn them I'm traveling and regardless eventually the pattern above always trips a lockdown on the card.
You'll be much better off taking out a couple hundred $$ every 3-4 days or so for gas, food and lodging and save the cards for big ticket items and emergencies.