This seems like an often sought feature, but all these high-level scripting approaches leave much to be desired (hacky, high overhead, not atomic, etc).
Just an idea. You can create a socket through socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL)) and capture ethernet frames, which you can then map MAC addresses to IP addresses and relay pairs to connected dumb APs.
Server: server -i interface -a address -p port
Client: client -a address -p port -s script.sh
Is this something people would be willing to compile for them their own devices?