Yes, Hirers can reduce their liability.
Accidents can happen to even the most careful drivers. Whilst the vehicle is in the hirer's care they are responsible for any damage, this includes damage caused by events they can’t control, such as hailstorms, or the vehicle being hit while parked.
Before the start of the trip, hirers have the option to decrease the excess required to pay out in the event of damage.
Hirers are invited to upgrade through the booking process and before their departure. It's not mandatory for the hirer to upgrade and you, as an owner, will not be impacted by which option they choose.
You can read more about the Hirer's Liability Waiver here - https://www.camplify.co.uk/liability-waiver