You would have to create the same L2 networks on the point side as what is needed on the portal side, enable the mesh into bridge mode AS WELL AS THE RAP on the point side to allow split tunneling (tunnel VLAN 1, bridge everything else). Then RAP traffic would bridge out of the RAP on the mesh point side into VLAN X/Y/Z, then get carried over tagged in VLAN X/Y/Z over the mesh link to the portal side. This requires you to have L2 switches connected to the point and portal, native on VLAN 1 (or whatever your current mgmt network is for your APs), trunked to carry VLAN X/Y/Z
That might work, but it's a fairly complex config.