It is entirely up to you if you wish to set a cleaning cost and a mileage limit as part of your booking conditions.
You can set them both by selecting "My Motorhome" and choosing the "Pricing" tab on the left-hand side of the page.
Mileage limit:
You will be able to set your mileage limit and a fee per extra mile.
Cleaning fee:
In the house rules, you can encourage a thorough cleaning by setting a cleaning fee (e.g. £30). This fee will be charged if the motorhome is not returned thoroughly clean.
If you do not set a fee, then you can state how you wish the vehicle to be returned and if it is not to the agreed standard then you will be able to add a cleaning fine which will be taken from the security deposit.
If you choose to set a fee, please make it clear in the house rules and on the GoForm how you expect the vehicle to be returned.