Restitution should be based on damage, not on the relative wealth of the victim and criminal.
The only change that I would consider would be to structure restitution similar to child support. The victim is paid in full at conviction. Any deficiency between what is paid and what is owed is loaned to the criminal by the state (at appropriate interest) and immediatly transfered to the victim.
i.e. the victim is paid in full at the time of conviction. If the criminal doesn’t have the funds to cover the full restitution, the long term payments are to the state, not to the victim.
Someone earlier in this thread mentioned a car that was going to be paid off at $13/mo forever. That is not fair. That delayed restitution damages a poor victim more than it does a rich victim. Using state funds to insure prompt payment of all restitutions would address the unfair result built into the existing system. (Perhaps “equitable” should be substituted for “fair” in that paragraph.)