Hi @Dan22480
Airbnb does allow hosts to require guests to sign a separate contract/rental agreement. However, you MUST disclose the actual contract language PRIOR to a guest booking. Most Hosts that do this post the language in Addl Rules and respond to a guest inquiry notifying them of the requirement to sign a separate agreement prior to booking and providing the exact language in a message to the guest. It does make for a pretty lengthy Add Rules section though. BTW, Vrbo allows Hosts to upload their own rental agreements to the listing; not sure about enforcing terms though.
That said, even if you have a signed rental agreement, there are no guarantees that a guest will comply or prevent someone from claiming tenancy after a 28day stay (in most states) even if your rental agreement states they are not a tenant.
Airbnb also states they cannot enforce any terms in your rental agreement:
Guest Contracts
https://www.airbnb.com/help/article/2824
If a Host asks you to sign a contract
https://www.airbnb.com/help/article/465
"Some Hosts ask guests to sign contracts or rental agreements. This is so the Host can legally enforce certain rules protecting themselves and their property. You should be made aware of this requirement before you book. The Host must prominently disclose the actual terms in their listing description. If you have questions about the contract, you can discuss it with the Host. You’re not obliged to sign anything. If a Host tells you about an additional contract after you’ve made a booking request, you should review the contract within 48 hours of receipt of the full terms. If you are not comfortable with it, you can decline to sign it and ask your Host to cancel your reservation without a cancellation penalty."
If you're planning on offering 28+ stays, I would definitely at least add that sub-letting is not allowed. Seems to be a big uptick in that lately.
I would do some of your own addl research and perhaps speak to an attorney, as most rental agreements must contain specific language to be valid and are state-specific.