You might have missed
a post containing an example of a dhcpd.conf in your PF-related thread. It would merely need to have the shared-network declaration removed, and the IP addresses changed to match your WiFi subnet.
For more on dhcpd configuration, you might find FAQ 6.4.2 helpful.
Edited to add:
Your netmasks need revision. in xl0, 255.0.10.0 isn't valid, and you have no netmask for athn0, and no "inet" declaration.