Vlan trunk over wlan

I don't get it. We already discussed it in detail.

I used gretap through any trusted IP connection. No matter if its WDS, wifi client, any VPN you like or powerlan. As long as you use gretap to tunnel through any IP connection, there's nearly no overhead to the tunnel itself ans you can easily use that gretap tunnel as vlan trunk assigning e.g. @trunk.100 for vlan 100.

See:

https://forum.openwrt.org/viewtopic.php?id=71080

I even provided you with a working example that I confirmed to be working on Virtualbox.