I personally think the most practical solution would be to legalise keeping exotics under a retricted and expensive permit only avialable to experienced keepers(to reduce escaping problems). Highly invasive species would be completely banned unless requied for special reasons.
End result: The exact same situation we are currently in with the addition of a few rich, experienced herpers keeping exotics legally.
No disrespect but you have contradicted yourself in that argument, if you want to legislate the already existing illegal trade of exotic reptiles in order to prevent escapes you will need to make the appropriate licensing available to those who currently posses these illegal animals.
I do agree with your point on harm minimisation but I don't feel that much can be done to locate and remove animals from people who simply should not have them.