To let a (trusted) person to attempt exploiting your security is basically the concept of penetration testing or "red teaming". It is a very common and recommended practice in security. Some industries even require such testing to be conducted periodically.
I want to hone in on the "full force" aspect:
Good pen tests should model real-world threats. Real-world threats absolutely can be 'full-force'; a skilled, focused, and determined hacker wouldn't hold back.
Usually pen tests set boundaries to avoid major disruption/damage to systems, but these boundaries may prevent testing for certain vulnerabilities. In other words, there is a balance. A good pen testing company can walk you through this and setup proper boundaries for your risk model.