@Jonathan47 Well, you can do a work around with your calendar. If you know when a returning guest might want to stay with you, you can block your calendar for them and give them your deadline in which to actually book (obviously you would have to unblock your calendar). You and you alone take whatever risks are involved. You know your customers best, after all. That said, I would not recommend other hosts at large do this as, what may work out for you , might not be a good solution for a hostwho is juggling many reservation requests.
Also, if you don't like the idea of Airbnb having the float from credit card payments so far in advance, shorten the availabiity of your calendar. I only allow reservations 4 months in advance. If you want people to be able to book months advance (I don't know how far in advance you allow people to book) and want to be guaranteed payment, then you have to allow Airbnb to hold the payment in escrow for you.
You can do this special "concierge" service for returning guests and I'm sure they would greatly appreciate it. It just takes a bit more management and time to keep track of everyone.