I dont' think you can. I'm petty sure that obfiscation parameters are build into AirBNB code and not configurable.
I woudl suggest posting in Host Voice a suggestion that for rural or low populatino areas that they show larger circle or provide option to turn off map. Might also have them suggest circle inlcude at least 3 other listings.
You can contact Air BNB - See the contact Airbnb post in the Community Help Guides - https://community.airbnb.com/t5/Community-Help/Community-Help-Guides/m-p/23100#M311
Skip down to the phone numbers and call them!!