Judgment of only 4-digit plate number

I am trying to use the alert feature to create a list of registered cars and manage the entry and exit of cars parked on company premises.
However, if the shooting conditions are poor, there are many misjudgments for Japanese contained in the plate, and the results are not as expected.
However, the four-digit plate number is always accurately detected.
Therefore, I want to judge only with these four-digit plate numbers. Can I do that?