AirBnb is not set up for you to rent your vehicle for off-site travel. You would need to get RV rental insurance from an insurance company. You might want to inquire with local RV rental companies about what insurance is available.
Just as with car rental, you pass that cost to your renter. You would absolutely NOT want to depend on the AirBnb security deposit or host insurance for this situation. It is very different than someone staying in your granny unit. They could crash the camper into a crowd of people. The liability is hugely enormous. Your camper could be 100% destroyed in seconds and people could be killed.
We rent our RV/camper through AirBnb but it is fixed on site just like a cabin would be. No one takes it off site.
Maybe there is a RV rental agency in your area and you could subcontract with them? You identify the renters through AirBnb, they pay you, then they go to the RV rental agency and fill in their paperwork and pay them for the insurance and associated fees.
As far as it being stolen, as soon as it is stolen you call the police and they look for it but probably never find it. The insurance you have for your possession comes into play. Personally if I were to do this I would get a GPS tracker installed in a hidden location and I would make sure I could track my property. I would require the guest to provide an itinerary and update it if it changed. I would not trust them.
For tickets and other costs that the guest should pay but does not, have a big security deposit. Detail in your written rental contract, in your listing and in person that these will be charged back if not paid. The problem you will encounter is that AirBnb requires you to identify and charge back these items within 48 hours and you will not likely know about them in that time frame.
Again, I would go to a local or national RV rental company and see if they want to 'lease' your RV for a small amount of money, and handle all the paperwork for you. You send them the renters, they rent them the RV and you collect the AirBnb funds and pay the RV company their portion.