Charles - if you're buying from an agent and he values your business, tell him you don't want to deal with the invasive crap and that he should place you with a more "business friendly" carrier.
The agent I was with when I started out put me with Celina Insurance. They wanted to audit by payroll hours. Their formulas for part time and full time (didn't correlate with seasonal) would have cost me about 15 to 20 man hours of office prep to convert numbers. I tried to work through it with them, but ultimately they said it had to be their way. I told them I wouldn't submit to an audit since they were being unreasonable.
I went to Grange Insurance through the same agent, avoiding the BS audit. Grange did it off of payroll dollars. My agent used to set the amount each year when we'd review the policy. Never had to show documentation.
I think it comes down to your agent, the carrier demands, and what your agent can do for you in that relationship. Find someone who values your business and understands your concerns and will find a less intrusive way to check the information.
Lawn Lad, Inc.