@Thomas3004 I have a detailed rental agreement, and the AirBnB website has no specific place to post or attach this for guest review, let alone signing and returning.
(VRBO does allow you to post your rental agreement for guest review but does not provide the means for a guest to sign it.)
What I would suggest is that you make it clear in your AirBnB listing that a rental agreement will be provided and that the guest must sign it prior to receiving the access instructions. I send my rental agreement to the guest immediately upon booking.
Fortunately for me, my state (NC) has a Vacation Rental Act that states that as long as I provide the rental agreement, the guest is presumed to have signed it by having paid for the reservation. I do not know if there is such a proviso for vacation rentals in New Jersey. Your attorney may be able to clarify this.