Insurance is important in case anything happens to your equipment while being rented. It's a no brainer and the cost is on the rentee not the renter. You can certainly rent in any fashion you like, with or without insurance, but it's worth the extra effort for all involved to have the piece of mind insurance provides.
It's the difference between a yelling match over who is responsible and actually getting a replacement unit if something does go awry.
We suggest an excellent firm Dewitt Stern that has been around since 1899 and specializes in short term production insurance.