Which BLE chip do you use? On the nRF51, it actually remaps -40dBm to -30dBm. With the newer nRF52, you can use NFC for OOB authentication for more security. I'd love to know more what you're working on.
The 52832 in a third party module and as you know that maps -30 to -40. NFC would have been nice but my hardware guy didn't bring the pins out on either side which is a damn shame because I don't have any user inputs other than power on/off on one side of the link. Email is in my profile if you'd like to know more