Buying fuel with credit card

I think where you find this practice it is because of the policy of the credit card (cc) company or the intermediary. It is common to see signs posted at hotels notifying that a charge against the anticipated costs will be placed on the credit card and may last a few days after departure. Same is true when purchasing diesel on the CC at many locations. You could use multiple CC at the point of purchase. One card until the pump stops, then the second card, and often you can use the first card again. That way you will only be charged for the fuel dispensed. Or, if purchasing inside, instead of saying "a fill up" specify a dollar amount less than you really need. You won't top off, but you will not have a carry over charge.
Happy Trails.