Yes, it could be possible to charge more than the security deposit if closeout charges related to the rental exceed that amount.
For example if the security deposit is $1,000 and a renter uses more mileage than originally set in the booking, totaling $1,200, then the renter will have to pay the additional $200 to cover the mileage charge.

One the other hand, in case of damages, or if the RV is not insured through RVezy, the maximum amount that can be charged to the renter is the security deposit.