A debit card, to be used for cash only, the trusty ATM machine, and a credit card for purchases. Keep ATM receipts until the next statement to check for duplicate charges. These are useful for keeping track of gas and oil purchases and use, and timing for bearings, brakes and slider upkeep. Trailer Life has a booklet which lists each state's tax burden. However, there are some hidden charges in many of them.
Careful scrutiny is required.
Other useful publications include the Motor Carriers Guide, a listing of truck stops which have laundries and ATMs, and which also shows trucker's routes. Short days and slow travel. Their idea for this lifestyle is enjoyment, and avoiding stress.