Three things come to mind:
- Pulley alignment
- Belt length
- Belt tightness
If the pulley's are aligned and the belt adjusted, then use the shortest belt you can. While I don't launch like you describe ( street car ), I regularly do 6500 shifts and have never lost a belt. This is with a standard depth pulley, using a short belt. I put a metal straightedge across the pulleys and shimmed to get as good an alignment as I could.
69 RS Conv,355,M20,4.10's and I don't worry about stone chips ( yet ).