Tunneling wlan traffic over gre with a vlan tag

I'd like to take traffic on a particular wlan and use a gretap tunnel to send it elsewhere at layer 2. So dhcp etc would be handled by the device terminating the gre tunnel over the WAN. I also need to tag the outgoing layer 2 inner header with a VLAN tag. So the wireless client talks with no VLAN tag but one is added by the router at ecapsulation and removed on return traffic to the client. This is basically how controller based APs work.

This is what I came up with just a cursory understanding of openWRT but I'm not seeing GRE encapped packets on tcpdumps of any of the interfaces.

config interface 'gre1'
        option proto 'gretap'
        option peeraddr ''
        option delegate '0'
        option mtu 1558

config interface 'br1'
        option type 'bridge'
        option stp '0'
        option ifname 'wlan2 @gre1.100'
        option delegate '0'

As far as I know, WLAN and VLAN do not play along nicely (or that is what I read around here). However, I have used an untagged GRE tunnel over a WLAN connection, then put several networks inside the tunnel using VLANs.

Having a @ in that name seems odd since it isn't a logical interface. And it's recommended to configure "network" in./etc/config/wireless config instead of using wlan interfaces in /etc/config/network.

The VLAN should never traverse wireless, it's only added to upstream packets and stripped from downstream, usually on a per SSID basis but that's not a requirement. Every public or corporate wifi you've ever connected to likely does this.