I use the verbage in the home business journal contact...that works great and provides the assurance you are looking for. If that is not enough for you then modify the verbage and print it on a separate parchment paper and make it a separate document you offer the customer.
The sample contracts that come in the HBJ kit are great, but they are generic and basic. I used them as a base and made many modifications and additions to fit what I needed and what works for me. I'm still modifying all of my contracts after several years, as I think of other things that needs to be added for coverage.
Contracts are a living document that need to be updated as your business progresses and to offer protection to you, the business owner as things change.
I use the verbage in the home business journal contact...that works great and provides the assurance you are looking for. If that is not enough for you then modify the verbage and print it on a separate parchment paper and make it a separate document you offer the customer.