Similar issue here, too!
The Instant Book system favours the guests and the Airbnb policy machine... If we could limit Instant Book for even 3 months ahead, that would be immensly helpful.
I had to decline a booking made for New Year 2018(!) The family must've been incredibly prompt to make their booking 1 year in advance. I was away at the time, and then had to decline the booking as the system will not let me block off dates as unavailable until those same dates are available for guests to book!
This cost my Superhost status, despite a 98% satisfaction rate.
I cannot get any response from Airbnb - it's an impossible task.
My mindset is now that Superhost merely means someone who hasn't upset Airbnb!!! THere are ways and means to spread the interpretation of what the Superhost tag represents!