Realtek WiFi adapters not recognized in custom Alpine Linux install

I am running Alpine Linux from a custom ISO that I created using the extended profile as a base (following instructions https://unix.stackexchange.com/questions/370895/install-packages-into-a-custom-alpine-linux-iso and https://wiki.alpinelinux.org/wiki/How_to_make_a_custom_ISO_image_with_mkimage) . Everything works perfectly, except it does not detect any wifi adapter (internal or USB). Running lshw seems to indicate both are Realtek. Just to be sure, I also did add the non-free b43 drivers as described here: https://wiki.alpinelinux.org/wiki/Connecting_to_a_wireless_access_point I have the same problem when running from RAM as I do when running on the sys install to hard disk. What am I missing here that I can't get the wifi working?