Restrict prospects loaded while Campaign Launch

Hello There,

This is regarding campaign launch functionality. List associated to campaign which has prospects will be loaded to campaign. We have custom field on prospect which may be updated after campaign load.

Based on the custom field value like region code, can we restrict to launch campaign only for those prospects which has region code as not null?. OOTB workflow Marketing Campaign Launch uses business service "Campaign Execution" method LaunchWaves to launch campaign for the wave selected. Is there a way to customize this or any other solution to achieve this. Please advise.

Basically we want to launch campaign for those prospects by constraining field region code