It’s always a good rule of thumb to use a safety-first approach, and that’s why all states require seat belts for all passengers either sitting upfront or throughout the cabin. The Outdoorsy terms and conditions state the following:
Guest acknowledges that Outdoorsy has no control over the number of passengers a guest may allow into the rental or the conduct of those occupants while the rental is being operated. Therefore, Host acknowledges that Guest is solely responsible for the passengers on board the rental as well as the conduct of those passengers, and Guest and Host shall confirm that both driver and passengers are properly using seat belts while the rental is in motion.
As our terms and conditions, Terms of Service (and inclusive verbiage such as below) are linked to Protection Package coverage requirements conditions:
'Guests are required to wear seat belts during the operation of the Vehicle and to require that all of their passengers wear seat belts. Guests are also required to meet any laws or regulations concerning child safety seats and other protections for children. Guests must not leave the Vehicle unlocked or with the keys unsecure (such as in the ignition)'
Your insurance coverage may be adversely impacted or denied as a renter in the event you or your passengers do not properly apply your seat belts.