802.1ad (Q-in-Q) setup

Maybe this post will help:

I guess just add to bridge vlan:

option vid '203.5'

5 being the "C tag" and 203 being the "S tag"

Got me thinking that this might help with "DSA roaming issues":

Would be like with MikroTik RouterOS CAP manager solution where there is only one VLAN between APs and AP CAP manager, and VLANs are defined on WLAN side .